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Rajendran K, Madhavan AA. Optimizing Photon-Counting Detector CT for Imaging Intracranial Aneurysms. AJNR Am J Neuroradiol 2024:ajnr.A8400. [PMID: 39122465 DOI: 10.3174/ajnr.a8400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2024]
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Fink N, Emrich T, Schoepf UJ, Zsarnoczay E, O'Doherty J, Halfmann MC, Griffith JP, Pinos D, Suranyi P, Baruah D, Kabakus IM, Ricke J, Varga-Szemes A. Improved Detection of Small and Low-Density Plaques in Virtual Noncontrast Imaging-based Calcium Scoring at Photon-Counting Detector CT. Radiol Cardiothorac Imaging 2024; 6:e230328. [PMID: 39023373 DOI: 10.1148/ryct.230328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Purpose To investigate the impact of plaque size and density on virtual noncontrast (VNC)-based coronary artery calcium scoring (CACS) using photon-counting detector CT and to provide safety net reconstructions for improved detection of subtle plaques in patients whose VNC-based CACS would otherwise be erroneously zero when compared with true noncontrast (TNC)-based CACS. Materials and Methods In this prospective study, CACS was evaluated in a phantom containing calcifications with different diameters (5, 3, and 1 mm) and densities (800, 400, and 200 mg/cm3) and in participants who underwent TNC and contrast-enhanced cardiac photon-counting detector CT (July 2021-March 2022). VNC images were reconstructed at different virtual monoenergetic imaging (55-80 keV) and quantum iterative reconstruction (QIR) levels (QIR,1-4). TNC scans at 70 keV with QIR off served as the reference standard. In vitro CACS was analyzed using standard settings (3.0-mm sections, kernel Qr36, 130-HU threshold). Calcification detectability and CACS of small and low-density plaques were also evaluated using 1.0-mm sections, kernel Qr44, and 120- or 110-HU thresholds. Safety net reconstructions were defined based on background Agatston scores and evaluated in vivo in TNC plaques initially nondetectable using standard VNC reconstructions. Results The in vivo cohort included 63 participants (57.8 years ± 15.5 [SD]; 37 [59%] male, 26 [41%] female). Correlation and agreement between standard CACSVNC and CACSTNC were higher in large- and medium-sized and high- and medium-density than in low-density plaques (in vitro: intraclass correlation coefficient [ICC] ≥ 0.90; r > 0.9 vs ICC = 0.20-0.48; r = 0.5-0.6). Small plaques were not detectable using standard VNC reconstructions. Calcification detectability was highest using 1.0-mm sections, kernel Qr44, 120- and 110-HU thresholds, and QIR level of 2 or less VNC reconstructions. Compared with standard VNC, using safety net reconstructions (55 keV, QIR 2, 110-HU threshold) for in vivo subtle plaque detection led to higher detection (increased by 89% [50 of 56]) and improved correlation and agreement of CACSVNC with CACSTNC (in vivo: ICC = 0.51-0.61; r = 0.6). Conclusion Compared with TNC-based calcium scoring, VNC-based calcium scoring was limited for small and low-density plaques but improved using safety net reconstructions, which may be particularly useful in patients with low calcium scores who would otherwise be treated based on potentially false-negative results. Keywords: Coronary Artery Calcium CT, Photon-Counting Detector CT, Virtual Noncontrast, Plaque Size, Plaque Density Supplemental material is available for this article. © RSNA, 2024.
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Affiliation(s)
- Nicola Fink
- From the Department of Radiology and Radiological Science, Division of Cardiovascular Imaging, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Dr, MUSC 226, Charleston, SC 29425-2260 (N.F., T.E., U.J.S., E.Z., J.O., J.P.G., D.P., P.S., D.B., I.M.K., A.V.S.); Department of Radiology, University Hospital, LMU Munich, Munich, Germany (N.F., J.R.); Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes Gutenberg-University, Mainz, Germany (T.E., M.C.H.); German Centre for Cardiovascular Research, Mainz, Germany (T.E.); Medical Imaging Center, Semmelweis University, Budapest, Hungary (E.Z.); and Siemens Medical Solutions, Malvern, Pa (J.O.)
| | - Tilman Emrich
- From the Department of Radiology and Radiological Science, Division of Cardiovascular Imaging, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Dr, MUSC 226, Charleston, SC 29425-2260 (N.F., T.E., U.J.S., E.Z., J.O., J.P.G., D.P., P.S., D.B., I.M.K., A.V.S.); Department of Radiology, University Hospital, LMU Munich, Munich, Germany (N.F., J.R.); Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes Gutenberg-University, Mainz, Germany (T.E., M.C.H.); German Centre for Cardiovascular Research, Mainz, Germany (T.E.); Medical Imaging Center, Semmelweis University, Budapest, Hungary (E.Z.); and Siemens Medical Solutions, Malvern, Pa (J.O.)
| | - U Joseph Schoepf
- From the Department of Radiology and Radiological Science, Division of Cardiovascular Imaging, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Dr, MUSC 226, Charleston, SC 29425-2260 (N.F., T.E., U.J.S., E.Z., J.O., J.P.G., D.P., P.S., D.B., I.M.K., A.V.S.); Department of Radiology, University Hospital, LMU Munich, Munich, Germany (N.F., J.R.); Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes Gutenberg-University, Mainz, Germany (T.E., M.C.H.); German Centre for Cardiovascular Research, Mainz, Germany (T.E.); Medical Imaging Center, Semmelweis University, Budapest, Hungary (E.Z.); and Siemens Medical Solutions, Malvern, Pa (J.O.)
| | - Emese Zsarnoczay
- From the Department of Radiology and Radiological Science, Division of Cardiovascular Imaging, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Dr, MUSC 226, Charleston, SC 29425-2260 (N.F., T.E., U.J.S., E.Z., J.O., J.P.G., D.P., P.S., D.B., I.M.K., A.V.S.); Department of Radiology, University Hospital, LMU Munich, Munich, Germany (N.F., J.R.); Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes Gutenberg-University, Mainz, Germany (T.E., M.C.H.); German Centre for Cardiovascular Research, Mainz, Germany (T.E.); Medical Imaging Center, Semmelweis University, Budapest, Hungary (E.Z.); and Siemens Medical Solutions, Malvern, Pa (J.O.)
| | - Jim O'Doherty
- From the Department of Radiology and Radiological Science, Division of Cardiovascular Imaging, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Dr, MUSC 226, Charleston, SC 29425-2260 (N.F., T.E., U.J.S., E.Z., J.O., J.P.G., D.P., P.S., D.B., I.M.K., A.V.S.); Department of Radiology, University Hospital, LMU Munich, Munich, Germany (N.F., J.R.); Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes Gutenberg-University, Mainz, Germany (T.E., M.C.H.); German Centre for Cardiovascular Research, Mainz, Germany (T.E.); Medical Imaging Center, Semmelweis University, Budapest, Hungary (E.Z.); and Siemens Medical Solutions, Malvern, Pa (J.O.)
| | - Moritz C Halfmann
- From the Department of Radiology and Radiological Science, Division of Cardiovascular Imaging, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Dr, MUSC 226, Charleston, SC 29425-2260 (N.F., T.E., U.J.S., E.Z., J.O., J.P.G., D.P., P.S., D.B., I.M.K., A.V.S.); Department of Radiology, University Hospital, LMU Munich, Munich, Germany (N.F., J.R.); Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes Gutenberg-University, Mainz, Germany (T.E., M.C.H.); German Centre for Cardiovascular Research, Mainz, Germany (T.E.); Medical Imaging Center, Semmelweis University, Budapest, Hungary (E.Z.); and Siemens Medical Solutions, Malvern, Pa (J.O.)
| | - Joseph P Griffith
- From the Department of Radiology and Radiological Science, Division of Cardiovascular Imaging, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Dr, MUSC 226, Charleston, SC 29425-2260 (N.F., T.E., U.J.S., E.Z., J.O., J.P.G., D.P., P.S., D.B., I.M.K., A.V.S.); Department of Radiology, University Hospital, LMU Munich, Munich, Germany (N.F., J.R.); Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes Gutenberg-University, Mainz, Germany (T.E., M.C.H.); German Centre for Cardiovascular Research, Mainz, Germany (T.E.); Medical Imaging Center, Semmelweis University, Budapest, Hungary (E.Z.); and Siemens Medical Solutions, Malvern, Pa (J.O.)
| | - Daniel Pinos
- From the Department of Radiology and Radiological Science, Division of Cardiovascular Imaging, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Dr, MUSC 226, Charleston, SC 29425-2260 (N.F., T.E., U.J.S., E.Z., J.O., J.P.G., D.P., P.S., D.B., I.M.K., A.V.S.); Department of Radiology, University Hospital, LMU Munich, Munich, Germany (N.F., J.R.); Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes Gutenberg-University, Mainz, Germany (T.E., M.C.H.); German Centre for Cardiovascular Research, Mainz, Germany (T.E.); Medical Imaging Center, Semmelweis University, Budapest, Hungary (E.Z.); and Siemens Medical Solutions, Malvern, Pa (J.O.)
| | - Pal Suranyi
- From the Department of Radiology and Radiological Science, Division of Cardiovascular Imaging, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Dr, MUSC 226, Charleston, SC 29425-2260 (N.F., T.E., U.J.S., E.Z., J.O., J.P.G., D.P., P.S., D.B., I.M.K., A.V.S.); Department of Radiology, University Hospital, LMU Munich, Munich, Germany (N.F., J.R.); Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes Gutenberg-University, Mainz, Germany (T.E., M.C.H.); German Centre for Cardiovascular Research, Mainz, Germany (T.E.); Medical Imaging Center, Semmelweis University, Budapest, Hungary (E.Z.); and Siemens Medical Solutions, Malvern, Pa (J.O.)
| | - Dhiraj Baruah
- From the Department of Radiology and Radiological Science, Division of Cardiovascular Imaging, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Dr, MUSC 226, Charleston, SC 29425-2260 (N.F., T.E., U.J.S., E.Z., J.O., J.P.G., D.P., P.S., D.B., I.M.K., A.V.S.); Department of Radiology, University Hospital, LMU Munich, Munich, Germany (N.F., J.R.); Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes Gutenberg-University, Mainz, Germany (T.E., M.C.H.); German Centre for Cardiovascular Research, Mainz, Germany (T.E.); Medical Imaging Center, Semmelweis University, Budapest, Hungary (E.Z.); and Siemens Medical Solutions, Malvern, Pa (J.O.)
| | - Ismail M Kabakus
- From the Department of Radiology and Radiological Science, Division of Cardiovascular Imaging, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Dr, MUSC 226, Charleston, SC 29425-2260 (N.F., T.E., U.J.S., E.Z., J.O., J.P.G., D.P., P.S., D.B., I.M.K., A.V.S.); Department of Radiology, University Hospital, LMU Munich, Munich, Germany (N.F., J.R.); Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes Gutenberg-University, Mainz, Germany (T.E., M.C.H.); German Centre for Cardiovascular Research, Mainz, Germany (T.E.); Medical Imaging Center, Semmelweis University, Budapest, Hungary (E.Z.); and Siemens Medical Solutions, Malvern, Pa (J.O.)
| | - Jens Ricke
- From the Department of Radiology and Radiological Science, Division of Cardiovascular Imaging, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Dr, MUSC 226, Charleston, SC 29425-2260 (N.F., T.E., U.J.S., E.Z., J.O., J.P.G., D.P., P.S., D.B., I.M.K., A.V.S.); Department of Radiology, University Hospital, LMU Munich, Munich, Germany (N.F., J.R.); Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes Gutenberg-University, Mainz, Germany (T.E., M.C.H.); German Centre for Cardiovascular Research, Mainz, Germany (T.E.); Medical Imaging Center, Semmelweis University, Budapest, Hungary (E.Z.); and Siemens Medical Solutions, Malvern, Pa (J.O.)
| | - Akos Varga-Szemes
- From the Department of Radiology and Radiological Science, Division of Cardiovascular Imaging, Medical University of South Carolina, Ashley River Tower, 25 Courtenay Dr, MUSC 226, Charleston, SC 29425-2260 (N.F., T.E., U.J.S., E.Z., J.O., J.P.G., D.P., P.S., D.B., I.M.K., A.V.S.); Department of Radiology, University Hospital, LMU Munich, Munich, Germany (N.F., J.R.); Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes Gutenberg-University, Mainz, Germany (T.E., M.C.H.); German Centre for Cardiovascular Research, Mainz, Germany (T.E.); Medical Imaging Center, Semmelweis University, Budapest, Hungary (E.Z.); and Siemens Medical Solutions, Malvern, Pa (J.O.)
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Racine D, Mergen V, Viry A, Frauenfelder T, Alkadhi H, Vitzthum V, Euler A. Photon-Counting Detector CT for Liver Lesion Detection-Optimal Virtual Monoenergetic Energy for Different Simulated Patient Sizes and Radiation Doses. Invest Radiol 2024; 59:554-560. [PMID: 38193782 DOI: 10.1097/rli.0000000000001060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
OBJECTIVES The aim of this study was to evaluate the optimal energy level of virtual monoenergetic images (VMIs) from photon-counting detector computed tomography (CT) for the detection of liver lesions as a function of phantom size and radiation dose. MATERIALS AND METHODS An anthropomorphic abdominal phantom with liver parenchyma and lesions was imaged on a dual-source photon-counting detector CT at 120 kVp. Five hypoattenuating lesions with a lesion-to-background contrast difference of -30 HU and -45 HU and 3 hyperattenuating lesions with +30 HU and +90 HU were used. The lesion diameter was 5-10 mm. Rings of fat-equivalent material were added to emulate medium- or large-sized patients. The medium size was imaged at a volume CT dose index of 5, 2.5, and 1.25 mGy and the large size at 5 and 2.5 mGy, respectively. Each setup was imaged 10 times. For each setup, VMIs from 40 to 80 keV at 5 keV increments were reconstructed with quantum iterative reconstruction at a strength level of 4 (QIR-4). Lesion detectability was measured as area under the receiver operating curve (AUC) using a channelized Hotelling model observer with 10 dense differences of Gaussian channels. RESULTS Overall, highest detectability was found at 65 and 70 keV for both hypoattenuating and hyperattenuating lesions in the medium and large phantom independent of radiation dose (AUC range, 0.91-1.0 for the medium and 0.94-0.99 for the large phantom, respectively). The lowest detectability was found at 40 keV irrespective of the radiation dose and phantom size (AUC range, 0.78-0.99). A more pronounced reduction in detectability was apparent at 40-50 keV as compared with 65-75 keV when radiation dose was decreased. At equal radiation dose, detection as a function of VMI energy differed stronger for the large size as compared with the medium-sized phantom (12% vs 6%). CONCLUSIONS Detectability of hypoattenuating and hyperattenuating liver lesions differed between VMI energies for different phantom sizes and radiation doses. Virtual monoenergetic images at 65 and 70 keV yielded highest detectability independent of phantom size and radiation dose.
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Affiliation(s)
- Damien Racine
- From the Institute of Radiation Physics, University Hospital Lausanne (CHUV), University of Lausanne, Lausanne, Switzerland (D.R., A.V., V.V.); Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland (V.M., T.F., H.A., A.E.); and Department of Radiology, Kantonsspital Baden, Baden, Switzerland (A.E.)
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Hoeijmakers EJI, Martens B, Hendriks BMF, Mihl C, Miclea RL, Backes WH, Wildberger JE, Zijta FM, Gietema HA, Nelemans PJ, Jeukens CRLPN. How subjective CT image quality assessment becomes surprisingly reliable: pairwise comparisons instead of Likert scale. Eur Radiol 2024; 34:4494-4503. [PMID: 38165429 PMCID: PMC11213789 DOI: 10.1007/s00330-023-10493-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 09/22/2023] [Accepted: 10/29/2023] [Indexed: 01/03/2024]
Abstract
OBJECTIVES The aim of this study is to improve the reliability of subjective IQ assessment using a pairwise comparison (PC) method instead of a Likert scale method in abdominal CT scans. METHODS Abdominal CT scans (single-center) were retrospectively selected between September 2019 and February 2020 in a prior study. Sample variance in IQ was obtained by adding artificial noise using dedicated reconstruction software, including reconstructions with filtered backprojection and varying iterative reconstruction strengths. Two datasets (each n = 50) were composed with either higher or lower IQ variation with the 25 original scans being part of both datasets. Using in-house developed software, six observers (five radiologists, one resident) rated both datasets via both the PC method (forcing observers to choose preferred scans out of pairs of scans resulting in a ranking) and a 5-point Likert scale. The PC method was optimized using a sorting algorithm to minimize necessary comparisons. The inter- and intraobserver agreements were assessed for both methods with the intraclass correlation coefficient (ICC). RESULTS Twenty-five patients (mean age 61 years ± 15.5; 56% men) were evaluated. The ICC for interobserver agreement for the high-variation dataset increased from 0.665 (95%CI 0.396-0.814) to 0.785 (95%CI 0.676-0.867) when the PC method was used instead of a Likert scale. For the low-variation dataset, the ICC increased from 0.276 (95%CI 0.034-0.500) to 0.562 (95%CI 0.337-0.729). Intraobserver agreement increased for four out of six observers. CONCLUSION The PC method is more reliable for subjective IQ assessment indicated by improved inter- and intraobserver agreement. CLINICAL RELEVANCE STATEMENT This study shows that the pairwise comparison method is a more reliable method for subjective image quality assessment. Improved reliability is of key importance for optimization studies, validation of automatic image quality assessment algorithms, and training of AI algorithms. KEY POINTS • Subjective assessment of diagnostic image quality via Likert scale has limited reliability. • A pairwise comparison method improves the inter- and intraobserver agreement. • The pairwise comparison method is more reliable for CT optimization studies.
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Affiliation(s)
- Eva J I Hoeijmakers
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, 6229 HX, The Netherlands.
| | - Bibi Martens
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, 6229 HX, The Netherlands
- CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, Maastricht, 6229 ER, The Netherlands
| | - Babs M F Hendriks
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, 6229 HX, The Netherlands
- CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, Maastricht, 6229 ER, The Netherlands
| | - Casper Mihl
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, 6229 HX, The Netherlands
- CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, Maastricht, 6229 ER, The Netherlands
| | - Razvan L Miclea
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, 6229 HX, The Netherlands
| | - Walter H Backes
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, 6229 HX, The Netherlands
- Department of Neurology and School for Mental health and Neuroscience (MheNs), Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, 6229 HX, The Netherlands
| | - Joachim E Wildberger
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, 6229 HX, The Netherlands
- CARIM School for Cardiovascular Diseases, Maastricht University, Universiteitssingel 50, Maastricht, 6229 ER, The Netherlands
| | - Frank M Zijta
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, 6229 HX, The Netherlands
| | - Hester A Gietema
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, 6229 HX, The Netherlands
- GROW School for Oncology and Reproduction, Maastricht University, Universiteitssingel 50, Maastricht, 6229 ER, The Netherlands
| | - Patricia J Nelemans
- Department of Epidemiology, Maastricht University, Universiteitssingel 50, Maastricht, 6229 ER, The Netherlands
| | - Cécile R L P N Jeukens
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre+, P. Debyelaan 25, Maastricht, 6229 HX, The Netherlands
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Vecsey-Nagy M, Varga-Szemes A, Schoepf UJ, Tremamunno G, Fink N, Zsarnoczay E, Szilveszter B, Graafen D, Halfmann MC, Vattay B, Boussoussou M, O'Doherty J, Suranyi PS, Maurovich-Horvat P, Emrich T. Ultra-high resolution coronary CT angiography on photon-counting detector CT: bi-centre study on the impact of quantum iterative reconstruction on image quality and accuracy of stenosis measurements. Eur J Radiol 2024; 176:111517. [PMID: 38805884 DOI: 10.1016/j.ejrad.2024.111517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Accepted: 05/17/2024] [Indexed: 05/30/2024]
Abstract
PURPOSE To assess the impact of different quantum iterative reconstruction (QIR) levels on objective and subjective image quality of ultra-high resolution (UHR) coronary CT angiography (CCTA) images and to determine the effect of strength levels on stenosis quantification using photon-counting detector (PCD)-CT. METHOD A dynamic vessel phantom containing two calcified lesions (25 % and 50 % stenosis) was scanned at heart rates of 60, 80 and 100 beats per minute with a PCD-CT system. In vivo CCTA examinations were performed in 102 patients. All scans were acquired in UHR mode (slice thickness0.2 mm) and reconstructed with four different QIR levels (1-4) using a sharp vascular kernel (Bv64). Image noise, signal-to-noise ratio (SNR), sharpness, and percent diameter stenosis (PDS) were quantified in the phantom, while noise, SNR, contrast-to-noise ratio (CNR), sharpness, and subjective quality metrics (noise, sharpness, overall image quality) were assessed in patient scans. RESULTS Increasing QIR levels resulted in significantly lower objective image noise (in vitro and in vivo: both p < 0.001), higher SNR (both p < 0.001) and CNR (both p < 0.001). Sharpness and PDS values did not differ significantly among QIRs (all pairwise p > 0.008). Subjective noise of in vivo images significantly decreased with increasing QIR levels, resulting in significantly higher image quality scores at increasing QIR levels (all pairwise p < 0.001). Qualitative sharpness, on the other hand, did not differ across different levels of QIR (p = 0.15). CONCLUSIONS The QIR algorithm may enhance the image quality of CCTA datasets without compromising image sharpness or accurate stenosis measurements, with the most prominent benefits at the highest strength level.
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Affiliation(s)
- Milan Vecsey-Nagy
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, United States; Heart and Vascular Centre, Semmelweis University, 68. Varosmajor street, Budapest 1122, Hungary
| | - Akos Varga-Szemes
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, United States
| | - U Joseph Schoepf
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, United States.
| | - Giuseppe Tremamunno
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, United States; Department of Medical Surgical Sciences and Translational Medicine, Sapienza University of Rome - Sant'Andrea University, Hospital Via di Grottarossa 1035-1039 00189 Rome, Italy
| | - Nicola Fink
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, United States; Department of Radiology, University Hospital, LMU Munich, Marchioninistraße 15, Munich 81377, Germany
| | - Emese Zsarnoczay
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, United States; MTA-SE Cardiovascular Imaging Research Group, Medical Imaging Centre, Semmelweis University, Koranyi Sandor street 2, Budapest 1083, Hungary
| | - Bálint Szilveszter
- Heart and Vascular Centre, Semmelweis University, 68. Varosmajor street, Budapest 1122, Hungary
| | - Dirk Graafen
- Department of Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University, Langenbeckstraße 1, Mainz 55131, Germany
| | - Moritz C Halfmann
- Department of Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University, Langenbeckstraße 1, Mainz 55131, Germany
| | - Borbála Vattay
- Heart and Vascular Centre, Semmelweis University, 68. Varosmajor street, Budapest 1122, Hungary
| | - Melinda Boussoussou
- Heart and Vascular Centre, Semmelweis University, 68. Varosmajor street, Budapest 1122, Hungary
| | - Jim O'Doherty
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, United States; Siemens Medical Solutions USA Inc, 40 Liberty Boulevard, Malvern, PA 19355, United States
| | - Pal Spruill Suranyi
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, United States
| | - Pál Maurovich-Horvat
- MTA-SE Cardiovascular Imaging Research Group, Medical Imaging Centre, Semmelweis University, Koranyi Sandor street 2, Budapest 1083, Hungary
| | - Tilman Emrich
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, United States; Department of Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University, Langenbeckstraße 1, Mainz 55131, Germany
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Gnasso C, Pinos D, Schoepf UJ, Vecsey-Nagy M, Aquino GJ, Fink N, Zsarnoczay E, Holtackers RJ, Stock J, Suranyi P, Varga-Szemes A, Emrich T. Impact of reconstruction parameters on the accuracy of myocardial extracellular volume quantification on a first-generation, photon-counting detector CT. Eur Radiol Exp 2024; 8:70. [PMID: 38890175 PMCID: PMC11189359 DOI: 10.1186/s41747-024-00469-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Accepted: 04/11/2024] [Indexed: 06/20/2024] Open
Abstract
BACKGROUND The potential role of cardiac computed tomography (CT) has increasingly been demonstrated for the assessment of diffuse myocardial fibrosis through the quantification of extracellular volume (ECV). Photon-counting detector (PCD)-CT technology may deliver more accurate ECV quantification compared to energy-integrating detector CT. We evaluated the impact of reconstruction settings on the accuracy of ECV quantification using PCD-CT, with magnetic resonance imaging (MRI)-based ECV as reference. METHODS In this post hoc analysis, 27 patients (aged 53.1 ± 17.2 years (mean ± standard deviation); 14 women) underwent same-day cardiac PCD-CT and MRI. Late iodine CT scans were reconstructed with different quantum iterative reconstruction levels (QIR 1-4), slice thicknesses (0.4-8 mm), and virtual monoenergetic imaging levels (VMI, 40-90 keV); ECV was quantified for each reconstruction setting. Repeated measures ANOVA and t-test for pairwise comparisons, Bland-Altman plots, and Lin's concordance correlation coefficient (CCC) were used. RESULTS ECV values did not differ significantly among QIR levels (p = 1.000). A significant difference was observed throughout different slice thicknesses, with 0.4 mm yielding the highest agreement with MRI-based ECV (CCC = 0.944); 45-keV VMI reconstructions showed the lowest mean bias (0.6, 95% confidence interval 0.1-1.4) compared to MRI. Using the most optimal reconstruction settings (QIR4. slice thickness 0.4 mm, VMI 45 keV), a 63% reduction in mean bias and a 6% increase in concordance with MRI-based ECV were achieved compared to standard settings (QIR3, slice thickness 1.5 mm; VMI 65 keV). CONCLUSIONS The selection of appropriate reconstruction parameters improved the agreement between PCD-CT and MRI-based ECV. RELEVANCE STATEMENT Tailoring PCD-CT reconstruction parameters optimizes ECV quantification compared to MRI, potentially improving its clinical utility. KEY POINTS • CT is increasingly promising for myocardial tissue characterization, assessing focal and diffuse fibrosis via late iodine enhancement and ECV quantification, respectively. • PCD-CT offers superior performance over conventional CT, potentially improving ECV quantification and its agreement with MRI-based ECV. • Tailoring PCD-CT reconstruction parameters optimizes ECV quantification compared to MRI, potentially improving its clinical utility.
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Affiliation(s)
- Chiara Gnasso
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC, 29425, USA
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Via Olgettina 60, Milan, Italy
| | - Daniel Pinos
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC, 29425, USA
| | - U Joseph Schoepf
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC, 29425, USA
| | - Milan Vecsey-Nagy
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC, 29425, USA
- Heart and Vascular Center, Semmelweis University, Varosmajor Utca 68, Budapest, 1122, Hungary
| | - Gilberto J Aquino
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC, 29425, USA
| | - Nicola Fink
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC, 29425, USA
- Department of Radiology, University Hospital, LMU Munich, Marchioninistr. 15, Munich, 81377, Germany
| | - Emese Zsarnoczay
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC, 29425, USA
- MTA-SE Cardiovascular Imaging Research Group, Department of Radiology, Medical Imaging Centre, Semmelweis University, Üllői Út 78, Budapest, 1082, Hungary
| | - Robert J Holtackers
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Centre, Maastricht, 6229 HX, The Netherlands
- Cardiovascular Research Institute Maastricht (CARIM), Maa stricht University, Maastricht, 6229 ER, The Netherlands
| | - Jonathan Stock
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC, 29425, USA
- Paracelsus Medical University, Prof.-Ernst-Nathan-Strasse 1, Nuremberg, 90419, Germany
| | - Pal Suranyi
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC, 29425, USA
| | - Akos Varga-Szemes
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC, 29425, USA
| | - Tilman Emrich
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC, 29425, USA.
- Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes Gutenberg-University, Langenbeckstr. 1, Mainz, 55131, Germany.
- German Centre for Cardiovascular Research, Mainz, 55131, Germany.
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Onishi H, Tsuboyama T, Nakamoto A, Ota T, Fukui H, Tatsumi M, Honda T, Kiso K, Matsumoto S, Kaketaka K, Enchi Y, Kawabata S, Nakasone S, Tomiyama N. Photon-counting CT: technical features and clinical impact on abdominal imaging. Abdom Radiol (NY) 2024:10.1007/s00261-024-04414-5. [PMID: 38888738 DOI: 10.1007/s00261-024-04414-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/25/2024] [Accepted: 05/27/2024] [Indexed: 06/20/2024]
Abstract
Photon-counting CT has a completely different detector mechanism than conventional energy-integrating CT. In the photon-counting detector, X-rays are directly converted into electrons and received as electrical signals. Photon-counting CT provides virtual monochromatic images with a high contrast-to-noise ratio for abdominal CT imaging and may improve the ability to visualize small or low-contrast lesions. In addition, photon-counting CT may offer the possibility of reducing radiation dose. This review provides an overview of the actual clinical operation of photon-counting CT and its diagnostic utility in abdominal imaging. We also describe the clinical implications of photon-counting CT including imaging of hepatocellular carcinoma, liver metastases, hepatic steatosis, pancreatic cancer, intraductal mucinous neoplasm of the pancreas, and thrombus.
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Affiliation(s)
- Hiromitsu Onishi
- Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan.
- Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Japan.
| | - Takahiro Tsuboyama
- Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Atsushi Nakamoto
- Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Takashi Ota
- Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Hideyuki Fukui
- Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Mitsuaki Tatsumi
- Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Toru Honda
- Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Kengo Kiso
- Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Shohei Matsumoto
- Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Koki Kaketaka
- Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan
| | - Yukihiro Enchi
- Division of Radiology, Department of Medical Technology, Osaka University Hospital, Suita, Japan
| | - Shuichi Kawabata
- Division of Radiology, Department of Medical Technology, Osaka University Hospital, Suita, Japan
| | - Shinya Nakasone
- Division of Radiology, Department of Medical Technology, Osaka University Hospital, Suita, Japan
| | - Noriyuki Tomiyama
- Department of Radiology, Osaka University Graduate School of Medicine, Suita, Japan
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8
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Neumann J, Nowak T, Schmidt B, von Zanthier J. An Image-Based Prior Knowledge-Free Approach for a Multi-Material Decomposition in Photon-Counting Computed Tomography. Diagnostics (Basel) 2024; 14:1262. [PMID: 38928677 PMCID: PMC11203122 DOI: 10.3390/diagnostics14121262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 06/07/2024] [Accepted: 06/13/2024] [Indexed: 06/28/2024] Open
Abstract
Photon-counting CT systems generally allow for acquiring multiple spectral datasets and thus for decomposing CT images into multiple materials. We introduce a prior knowledge-free deterministic material decomposition approach for quantifying three material concentrations on a commercial photon-counting CT system based on a single CT scan. We acquired two phantom measurement series: one to calibrate and one to test the algorithm. For evaluation, we used an anthropomorphic abdominal phantom with inserts of either aqueous iodine solution, aqueous tungsten solution, or water. Material CT numbers were predicted based on a polynomial in the following parameters: Water-equivalent object diameter, object center-to-isocenter distance, voxel-to-isocenter distance, voxel-to-object center distance, and X-ray tube current. The material decomposition was performed as a generalized least-squares estimation. The algorithm provided material maps of iodine, tungsten, and water with average estimation errors of 4% in the contrast agent maps and 1% in the water map with respect to the material concentrations in the inserts. The contrast-to-noise ratio in the iodine and tungsten map was 36% and 16% compared to the noise-minimal threshold image. We were able to decompose four spectral images into iodine, tungsten, and water.
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Affiliation(s)
- Jonas Neumann
- Quantum Optics and Quantum Information Group (QOQI), Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 1, 91058 Erlangen, Germany
- Siemens Healthineers AG, Siemensstr. 3, 91301 Forchheim, Germany
| | - Tristan Nowak
- Siemens Healthineers AG, Siemensstr. 3, 91301 Forchheim, Germany
| | - Bernhard Schmidt
- Siemens Healthineers AG, Siemensstr. 3, 91301 Forchheim, Germany
| | - Joachim von Zanthier
- Quantum Optics and Quantum Information Group (QOQI), Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 1, 91058 Erlangen, Germany
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Skornitzke S, Mergen V, Biederer J, Alkadhi H, Do TD, Stiller W, Frauenfelder T, Kauczor HU, Euler A. Metal Artifact Reduction in Photon-Counting Detector CT: Quantitative Evaluation of Artifact Reduction Techniques. Invest Radiol 2024; 59:442-449. [PMID: 37812482 DOI: 10.1097/rli.0000000000001036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
OBJECTIVES With the introduction of clinical photon-counting detector computed tomography (PCD-CT) and its novel reconstruction techniques, a quantitative investigation of different acquisition and reconstruction settings is necessary to optimize clinical acquisition protocols for metal artifact reduction. MATERIALS AND METHODS A multienergy phantom was scanned on a clinical dual-source PCD-CT (NAEOTOM Alpha; Siemens Healthcare GmbH) with 4 different central inserts: water-equivalent plastic, aluminum, steel, and titanium. Acquisitions were performed at 120 kVp and 140 kVp (CTDI vol 10 mGy) and reconstructed as virtual monoenergetic images (VMIs; 110-150 keV), as T3D, and with the standard reconstruction "none" (70 keV VMI) using different reconstruction kernels (Br36, Br56) and with as well as without iterative metal artifact reduction (iMAR). Metal artifacts were quantified, calculating relative percentages of metal artifacts. Mean CT numbers of an adjacent water-equivalent insert and different tissue-equivalent inserts were evaluated, and eccentricity of metal rods was measured. Repeated-measures analysis of variance was performed for statistical analysis. RESULTS Metal artifacts were most prevalent for the steel insert (12.6% average artifacts), followed by titanium (4.2%) and aluminum (1.0%). The strongest metal artifact reduction was noted for iMAR (with iMAR: 1.4%, without iMAR: 10.5%; P < 0.001) or VMI (VMI: 110 keV 2.6% to 150 keV 3.3%, T3D: 11.0%, and none: 16.0%; P < 0.001) individually, with best results when combining iMAR and VMI at 110 keV (1.2%). Changing acquisition tube potential (120 kV: 6.6%, 140 kV: 5.2%; P = 0.33) or reconstruction kernel (Br36: 5.5%, Br56: 6.4%; P = 0.17) was less effective. Mean CT numbers and standard deviations were significantly affected by iMAR (with iMAR: -3.0 ± 21.5 HU, without iMAR: -8.5 ± 24.3 HU; P < 0.001), VMI (VMI: 110 keV -3.6 ± 21.6 HU to 150 keV -1.4 ± 21.2 HU, T3D: -11.7 ± 23.8 HU, and none: -16.9 ± 29.8 HU; P < 0.001), tube potential (120 kV: -4.7 ± 22.8 HU, 140 kV: -6.8 ± 23.0 HU; P = 0.03), and reconstruction kernel (Br36: -5.5 ± 14.2 HU, Br56: -6.8 ± 23.0 HU; P < 0.001). Both iMAR and VMI improved quantitative CT number accuracy and metal rod eccentricity for the steel rod, but iMAR was of limited effectiveness for the aluminum rod. CONCLUSIONS For metal artifact reduction in PCD-CT, a combination of iMAR and VMI at 110 keV demonstrated the strongest artifact reduction of the evaluated options, whereas the impact of reconstruction kernel and tube potential was limited.
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Affiliation(s)
- Stephan Skornitzke
- From the Heidelberg University Hospital, Clinic for Diagnostic and Interventional Radiology, Heidelberg, Germany (S.S., J.B., T.D.D., W.S., and H.-U.K.); Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland (V.M., H.A., T.F., and A.E.); Translational Lung Research Center Heidelberg, Member of the German Lung Research Center, Heidelberg, Germany (J.B., W.S., H.-U.K.); University of Latvia, Faculty of Medicine, Riga, Latvia (J.B.); Christian-Albrechts-Universität zu Kiel, Faculty of Medicine, Kiel, Germany (J.B.); and Kantonsspital Baden, Radiologie Baden, Baden, Switzerland (A.E.)
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10
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Bette S, Risch F, Becker J, Popp D, Decker JA, Kaufmann D, Friedrich L, Scheurig-Münkler C, Schwarz F, Kröncke TJ. Photon-counting detector CT - first experiences in the field of musculoskeletal radiology. ROFO-FORTSCHR RONTG 2024. [PMID: 38788741 DOI: 10.1055/a-2312-6914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2024]
Abstract
The introduction of photon-counting detector CT (PCD-CT) marks a remarkable leap in innovation in CT imaging. The new detector technology allows X-rays to be converted directly into an electrical signal without an intermediate step via a scintillation layer and allows the energy of individual photons to be measured. Initial data show high spatial resolution, complete elimination of electronic noise, and steady availability of spectral image data sets. In particular, the new technology shows promise with respect to the imaging of osseous structures. Recently, PCD-CT was implemented in the clinical routine. The aim of this review was to summarize recent studies and to show our first experiences with photon-counting detector technology in the field of musculoskeletal radiology.We performed a literature search using Medline and included a total of 90 articles and reviews that covered recent experimental and clinical experiences with the new technology.In this review, we focus on (1) spatial resolution and delineation of fine anatomic structures, (2) reduction of radiation dose, (3) electronic noise, (4) techniques for metal artifact reduction, and (5) possibilities of spectral imaging. This article provides insight into our first experiences with photon-counting detector technology and shows results and images from experimental and clinical studies. · This review summarizes recent experimental and clinical studies in the field of photon-counting detector CT and musculoskeletal radiology.. · The potential of photon-counting detector technology in the field of musculoskeletal radiology includes improved spatial resolution, reduction in radiation dose, metal artifact reduction, and spectral imaging.. · PCD-CT enables imaging at lower radiation doses while maintaining or even enhancing spatial resolution, crucial for reducing patient exposure, especially in repeated or prolonged imaging scenarios.. · It offers promising results in reducing metal artifacts commonly encountered in orthopedic or dental implants, enhancing the interpretability of adjacent structures in postoperative and follow-up imaging.. · With its ability to routinely acquire spectral data, PCD-CT scans allow for material classification, such as detecting urate crystals in suspected gout or visualizing bone marrow edema, potentially reducing reliance on MRI in certain cases.. Bette S, Risch F, Becker J et al. Photon-counting detector CT - first experiences in the field of musculoskeletal radiology. Fortschr Röntgenstr 2024; DOI 10.1055/a-2312-6914.
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Affiliation(s)
- Stefanie Bette
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Augsburg, Germany
| | - Franka Risch
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Augsburg, Germany
| | - Judith Becker
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Augsburg, Germany
| | - Daniel Popp
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Augsburg, Germany
| | - Josua A Decker
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Augsburg, Germany
| | - David Kaufmann
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Augsburg, Germany
| | - Lena Friedrich
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Augsburg, Germany
| | - Christian Scheurig-Münkler
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Augsburg, Germany
| | - Florian Schwarz
- Institute of Conventional and Interventional Radiology, Donauisar Hospital Deggendorf, Deggendorf, Germany
| | - Thomas J Kröncke
- Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Augsburg, Augsburg, Germany
- Centre for Advanced Analytics and Predictive Sciences (CAAPS), University of Augsburg, Augsburg, Germany
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Toia GV, Mileto A, Borhani AA, Chen GH, Ren L, Uyeda JW, Marin D. Approaches, advantages, and challenges to photon counting detector and multi-energy CT. Abdom Radiol (NY) 2024:10.1007/s00261-024-04357-x. [PMID: 38744702 DOI: 10.1007/s00261-024-04357-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 04/21/2024] [Accepted: 04/21/2024] [Indexed: 05/16/2024]
Abstract
Photon counting detector CT (PCD-CT) is the newest major development in CT technology and has been commercially available since 2021. It offers major technological advantages over current standard-of-care energy integrating detector CT (EID-CT) including improved spatial resolution, improved iodine contrast to noise ratio, multi-energy imaging, and reduced noise. This article serves as a foundational basis to the technical approaches and concepts of PCD-CT technology with primary emphasis on detector technology in direct comparison to EID-CT. The article also addresses current technological challenges to PCD-CT with particular attention to cross talk and its causes (e.g., Compton scattering, fluorescence, charge sharing, K-escape) as well as pile-up.
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Affiliation(s)
- Giuseppe V Toia
- Departments of Radiology and Medical Physics, University of Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI, 53792, USA.
| | - Achille Mileto
- Department of Radiology, University of Washington, Seattle, WA, USA
| | - Amir A Borhani
- Department of Radiology, Northwestern University, Chicago, IL, USA
| | - Guang-Hong Chen
- Departments of Radiology and Medical Physics, University of Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI, 53792, USA
| | - Liqiang Ren
- Department of Radiology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Jennifer W Uyeda
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Daniele Marin
- Department of Radiology, Duke University Health System, Durham, NC, USA
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12
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McDermott MC, Sartoretti T, Stammen L, Martens B, Jost G, Pietsch H, Gutjahr R, Schmidt B, Flohr TG, Alkadhi H, Wildberger JE. Countering Calcium Blooming With Personalized Contrast Media Injection Protocols: The 1-2-3 Rule for Photon-Counting Detector CCTA. Invest Radiol 2024:00004424-990000000-00217. [PMID: 38742928 DOI: 10.1097/rli.0000000000001078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
OBJECTIVE Photon-counting detector computed tomography (PCD-CT) enables spectral data acquisition of CT angiographies allowing for reconstruction of virtual monoenergetic images (VMIs) in routine practice. Specifically, it has potential to reduce the blooming artifacts associated with densely calcified plaques. However, calcium blooming and iodine attenuation are inversely affected by energy level (keV) of the VMIs, creating a challenge for contrast media (CM) injection protocol optimization. A pragmatic and simple rule for calcium-dependent CM injection protocols is investigated and proposed for VMI-based coronary CT angiography with PCD-CT. MATERIALS AND METHODS A physiological circulation phantom with coronary vessels including calcified lesions (maximum CT value >700 HU) with a 50% diameter stenosis was injected into at iodine delivery rates (IDRs) of 0.3, 0.5, 0.7, 1.0, 1.5, 2.0, 2.5, and 3.0 g I/s. Images were acquired using a first-generation dual-source PCD-CT and reconstructed at various VMI levels (between 45 and 190 keV). Iodine attenuation in the coronaries was measured at each IDR for each keV, and blooming artifacts from the calcified lesions were assessed including stenosis grading error (as % overestimation vs true lumen). The IDR to achieve 300 HU at each VMI level was then calculated and compared with stenosis grading accuracy to establish a general rule for CM injection protocols. RESULTS Plaque blooming artifacts and intraluminal iodine attenuation decreased with increasing keV. Fixed windowing (representing absolute worst case) resulted in stenosis overestimation from 77% ± 4% at 45 keV to 5% ± 2% at 190 keV, whereas optimized windowing resulted in overestimation from 29% ± 3% at 45 keV to 4% ± 1% at 190 keV. The required IDR to achieve 300 HU showed a strong linear correlation to VMI energy (R2 = 0.98). Comparison of this linear plot versus stenosis grading error and blooming artifact demonstrated that multipliers of 1, 2, and 3 times the reference IDR for theoretical clinical regimes of no, moderate, and severe calcification density, respectively, can be proposed as a general rule. CONCLUSIONS This study provides a proof-of-concept in an anthropomorphic phantom for a simple pragmatic adaptation of CM injection protocols in coronary CT angiography with PCD-CT. The 1-2-3 rule demonstrates the potential for reducing the effects of calcium blooming artifacts on overall image quality.
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Affiliation(s)
- Michael C McDermott
- From the Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, the Netherlands (M.C.M., T.S., L.S., B.M., T.G.F., J.E.W.); Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland (T.S., H.A.); Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, the Netherlands (M.C.M., T.S., L.S., B.M., J.E.W.); Bayer AG, Berlin, Germany (M.C.M., G.J., H.P.); and Computed Tomography Division, Siemens Healthineers AG, Forchheim, Germany (R.G., B.S., T.G.F.)
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13
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Rajagopal JR, Schwartz FR, McCabe C, Farhadi F, Zarei M, Ria F, Abadi E, Segars P, Ramirez-Giraldo JC, Jones EC, Henry T, Marin D, Samei E. Technology Characterization Through Diverse Evaluation Methodologies: Application to Thoracic Imaging in Photon-Counting Computed Tomography. J Comput Assist Tomogr 2024:00004728-990000000-00312. [PMID: 38626754 DOI: 10.1097/rct.0000000000001608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/18/2024]
Abstract
OBJECTIVE Different methods can be used to condition imaging systems for clinical use. The purpose of this study was to assess how these methods complement one another in evaluating a system for clinical integration of an emerging technology, photon-counting computed tomography (PCCT), for thoracic imaging. METHODS Four methods were used to assess a clinical PCCT system (NAEOTOM Alpha; Siemens Healthineers, Forchheim, Germany) across 3 reconstruction kernels (Br40f, Br48f, and Br56f). First, a phantom evaluation was performed using a computed tomography quality control phantom to characterize noise magnitude, spatial resolution, and detectability. Second, clinical images acquired using conventional and PCCT systems were used for a multi-institutional reader study where readers from 2 institutions were asked to rank their preference of images. Third, the clinical images were assessed in terms of in vivo image quality characterization of global noise index and detectability. Fourth, a virtual imaging trial was conducted using a validated simulation platform (DukeSim) that models PCCT and a virtual patient model (XCAT) with embedded lung lesions imaged under differing conditions of respiratory phase and positional displacement. Using known ground truth of the patient model, images were evaluated for quantitative biomarkers of lung intensity histograms and lesion morphology metrics. RESULTS For the physical phantom study, the Br56f kernel was shown to have the highest resolution despite having the highest noise and lowest detectability. Readers across both institutions preferred the Br56f kernel (71% first rank) with a high interclass correlation (0.990). In vivo assessments found superior detectability for PCCT compared with conventional computed tomography but higher noise and reduced detectability with increased kernel sharpness. For the virtual imaging trial, Br40f was shown to have the best performance for histogram measures, whereas Br56f was shown to have the most precise and accurate morphology metrics. CONCLUSION The 4 evaluation methods each have their strengths and limitations and bring complementary insight to the evaluation of PCCT. Although no method offers a complete answer, concordant findings between methods offer affirmatory confidence in a decision, whereas discordant ones offer insight for added perspective. Aggregating our findings, we concluded the Br56f kernel best for high-resolution tasks and Br40f for contrast-dependent tasks.
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Affiliation(s)
| | - Fides R Schwartz
- Duke University Health System, Department of Radiology, Duke University Medical Center, Durham, NC
| | - Cindy McCabe
- From the Center for Virtual Imaging Trials, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC
| | | | - Mojtaba Zarei
- From the Center for Virtual Imaging Trials, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC
| | - Francesco Ria
- From the Center for Virtual Imaging Trials, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC
| | - Ehsan Abadi
- From the Center for Virtual Imaging Trials, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC
| | - Paul Segars
- From the Center for Virtual Imaging Trials, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC
| | | | - Elizabeth C Jones
- Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD
| | - Travis Henry
- Duke University Health System, Department of Radiology, Duke University Medical Center, Durham, NC
| | - Daniele Marin
- Duke University Health System, Department of Radiology, Duke University Medical Center, Durham, NC
| | - Ehsan Samei
- From the Center for Virtual Imaging Trials, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC
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Spampinato MV, Rodgers J, McGill LJ, Schoepf UJ, O'Doherty J. Image quality of photon-counting detector CT virtual monoenergetic and polyenergetic reconstructions for head and neck CT angiography. Clin Imaging 2024; 108:110081. [PMID: 38340435 DOI: 10.1016/j.clinimag.2024.110081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 11/09/2023] [Accepted: 01/07/2024] [Indexed: 02/12/2024]
Abstract
We compared image quality of head and neck CT angiography (CTA) obtained with a photon-counting detector CT (PCD-CT), including virtual monoenergetic images and polyenergetic reconstructions, and conventional energy-integrating detectors CT (EID-CT) in three patients. PCD-CT monoenergetic reconstructions at 70 keV and lower provided excellent image quality, with improved signal-to-noise and contrast-to-noise compared to EID-CT and PCD-CT polyenergetic reconstructions. PCD-CT may enable radiation dose and iodinated contrast dose reduction for cerebrovascular imaging.
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Affiliation(s)
- Maria Vittoria Spampinato
- Department of Radiology and Radiological Science, Medical University of South Carolina, 96 Jonathan Lucas Street, Charleston, SC 29425, United States of America.
| | - Jeffrey Rodgers
- College of Medicine, Medical University of South Carolina, 171 Ashley Avenue Charleston, SC 29425, United States of America
| | - Liam J McGill
- Department of Radiology and Radiological Science, Medical University of South Carolina, 96 Jonathan Lucas Street, Charleston, SC 29425, United States of America
| | - Uwe Joseph Schoepf
- Department of Radiology and Radiological Science, Medical University of South Carolina, 96 Jonathan Lucas Street, Charleston, SC 29425, United States of America
| | - Jim O'Doherty
- Department of Radiology and Radiological Science, Medical University of South Carolina, 96 Jonathan Lucas Street, Charleston, SC 29425, United States of America; Siemens Medical Solutions, 40 Liberty Blvd, Malvern, PA 19355, United States of America
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Huflage H, Hendel R, Kunz AS, Ergün S, Afat S, Petri N, Hartung V, Gruschwitz P, Bley TA, Grunz JP. Investigating the Small Pixel Effect in Ultra-High Resolution Photon-Counting CT of the Lung. Invest Radiol 2024; 59:293-297. [PMID: 37552040 DOI: 10.1097/rli.0000000000001013] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/09/2023]
Abstract
OBJECTIVES The aim of this study was to investigate potential benefits of ultra-high resolution (UHR) over standard resolution scan mode in ultra-low dose photon-counting detector CT (PCD-CT) of the lung. MATERIALS AND METHODS Six cadaveric specimens were examined with 5 dose settings using tin prefiltration, each in UHR (120 × 0.2 mm) and standard mode (144 × 0.4 mm), on a first-generation PCD-CT scanner. Image quality was evaluated quantitatively by noise comparisons in the trachea and both main bronchi. In addition, 16 readers (14 radiologists and 2 internal medicine physicians) independently completed a browser-based pairwise forced-choice comparison task for assessment of subjective image quality. The Kendall rank coefficient ( W ) was calculated to assess interrater agreement, and Pearson's correlation coefficient ( r ) was used to analyze the relationship between noise measurements and image quality rankings. RESULTS Across all dose levels, image noise in UHR mode was lower than in standard mode for scan protocols matched by CTDI vol ( P < 0.001). UHR examinations exhibited noise levels comparable to the next higher dose setting in standard mode ( P ≥ 0.275). Subjective ranking of protocols based on 5760 pairwise tests showed high interrater agreement ( W = 0.99; P ≤ 0.001) with UHR images being preferred by readers in the majority of comparisons. Irrespective of scan mode, a substantial indirect correlation was observed between image noise and subjective image quality ranking ( r = -0.97; P ≤ 0.001). CONCLUSIONS In PCD-CT of the lung, UHR scan mode reduces image noise considerably over standard resolution acquisition. Originating from the smaller detector element size in fan direction, the small pixel effect allows for superior image quality in ultra-low dose examinations with considerable potential for radiation dose reduction.
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Affiliation(s)
- Henner Huflage
- From the Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Würzburg, Germany (H.H., R.H., A.S., V.H., P.G., T.A., J.-P.G.); Institute of Anatomy and Cell Biology, University of Würzburg, Würzburg, Germany (S.E.); Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen, Germany (S.A.); and Department of Internal Medicine I, University Hospital Würzburg, Würzburg, Germany (N.P.)
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Michael AE, Schoenbeck D, Woeltjen MM, Boriesosdick J, Kroeger JR, Moenninghoff C, Horstmeier S, Niehoff JH, Kabbasch C, Goertz L, Borggrefe J. Nonenhanced Photon Counting CT of the Head : Impact of the keV Level, Iterative Reconstruction and Calvaria on Image Quality in Monoenergetic Images. Clin Neuroradiol 2024; 34:75-83. [PMID: 37589739 PMCID: PMC10881631 DOI: 10.1007/s00062-023-01331-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 07/02/2023] [Indexed: 08/18/2023]
Abstract
PURPOSE Nonenhanced computed tomography (CT) of the head is among the most commonly performed CT examinations. The spectral information acquired by photon counting CT (PCCT) allows generation of virtual monoenergetic images (VMI). At the same time, image noise can be reduced using quantum iterative reconstruction (QIR). In this study, the image quality of VMI was evaluated depending on the keV level and the QIR level. Furthermore, the influence of the cranial calvaria was investigated to determine the optimal reconstruction for clinical application. METHODS A total of 51 PCCT (NAEOTOM Alpha, Siemens Healthineers, Erlangen, Germany) of the head were retrospectively analyzed. In a quantitative analysis, gray and white matter ROIs were evaluated in different brain areas at all available keV levels and QIR levels with respect to signal, noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). The distance to the cranial calvaria of the ROIs was included in the analysis. This was followed by a qualitative reading by five radiologists including experienced neuroradiologists. RESULTS In most ROIs, signal and noise varied significantly between keV levels (p < 0.0001). The CNR had a focal maximum at 66 keV and an absolute maximum at higher keV, slightly differently located depending on ROI and QIR level. With increasing QIR level, a significant reduction in noise was achieved (p < 0.0001) except just beneath the cranial calvaria. The cranial calvaria had a strong effect on the signal (p < 0.0001) but not on gray and white matter noise. In the qualitative reading, the 60 keV VMI was rated best. CONCLUSION In nonenhanced PCCT of the head the selected keV level of the VMI and the QIR level have a crucial influence on image quality in VMI. The 60 keV and 66 keV VMI with high QIR level provided optimal subjective and objective image quality for clinical use. The cranial calvaria has a significant influence on the visualization of the adjacent brain matter; currently, this substantially limits the use of low keV VMIs (< 60 keV).
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Affiliation(s)
- Arwed Elias Michael
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, Bochum, Germany.
- Johannes Wesling University Hospital by Muehlenkreiskliniken AöR, Hans-Nolte-Straße 1, 32429, Minden, Germany.
| | - Denise Schoenbeck
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, Bochum, Germany
| | - Matthias Michael Woeltjen
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, Bochum, Germany
| | - Jan Boriesosdick
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, Bochum, Germany
| | - Jan Robert Kroeger
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, Bochum, Germany
| | - Christoph Moenninghoff
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, Bochum, Germany
| | - Sebastian Horstmeier
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, Bochum, Germany
| | - Julius Henning Niehoff
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, Bochum, Germany
| | - Christoph Kabbasch
- Department of Radiology and Neuroradiology, University Hospital of Cologne, Cologne, Germany
| | - Lukas Goertz
- Department of Radiology and Neuroradiology, University Hospital of Cologne, Cologne, Germany
| | - Jan Borggrefe
- Department of Radiology, Neuroradiology and Nuclear Medicine, Johannes Wesling University Hospital, Ruhr University Bochum, Bochum, Germany
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Sartoretti T, Skawran S, Gennari AG, Maurer A, Euler A, Treyer V, Sartoretti E, Waelti S, Schwyzer M, von Schulthess GK, Burger IA, Huellner MW, Messerli M. Fully automated computational measurement of noise in positron emission tomography. Eur Radiol 2024; 34:1716-1723. [PMID: 37644149 PMCID: PMC10873217 DOI: 10.1007/s00330-023-10056-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 04/15/2023] [Accepted: 05/15/2023] [Indexed: 08/31/2023]
Abstract
OBJECTIVES To introduce an automated computational algorithm that estimates the global noise level across the whole imaging volume of PET datasets. METHODS [18F]FDG PET images of 38 patients were reconstructed with simulated decreasing acquisition times (15-120 s) resulting in increasing noise levels, and with block sequential regularized expectation maximization with beta values of 450 and 600 (Q.Clear 450 and 600). One reader performed manual volume-of-interest (VOI) based noise measurements in liver and lung parenchyma and two readers graded subjective image quality as sufficient or insufficient. An automated computational noise measurement algorithm was developed and deployed on the whole imaging volume of each reconstruction, delivering a single value representing the global image noise (Global Noise Index, GNI). Manual noise measurement values and subjective image quality gradings were compared with the GNI. RESULTS Irrespective of the absolute noise values, there was no significant difference between the GNI and manual liver measurements in terms of the distribution of noise values (p = 0.84 for Q.Clear 450, and p = 0.51 for Q.Clear 600). The GNI showed a fair to moderately strong correlation with manual noise measurements in liver parenchyma (r = 0.6 in Q.Clear 450, r = 0.54 in Q.Clear 600, all p < 0.001), and a fair correlation with manual noise measurements in lung parenchyma (r = 0.52 in Q.Clear 450, r = 0.33 in Q.Clear 600, all p < 0.001). Classification performance of the GNI for subjective image quality was AUC 0.898 for Q.Clear 450 and 0.919 for Q.Clear 600. CONCLUSION An algorithm provides an accurate and meaningful estimation of the global noise level encountered in clinical PET imaging datasets. CLINICAL RELEVANCE STATEMENT An automated computational approach that measures the global noise level of PET imaging datasets may facilitate quality standardization and benchmarking of clinical PET imaging within and across institutions. KEY POINTS • Noise is an important quantitative marker that strongly impacts image quality of PET images. • An automated computational noise measurement algorithm provides an accurate and meaningful estimation of the global noise level encountered in clinical PET imaging datasets. • An automated computational approach that measures the global noise level of PET imaging datasets may facilitate quality standardization and benchmarking as well as protocol harmonization.
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Affiliation(s)
- Thomas Sartoretti
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland
| | - Stephan Skawran
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
| | - Antonio G Gennari
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
| | - Alexander Maurer
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
| | - André Euler
- University of Zurich, Zurich, Switzerland
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, Zurich, Switzerland
| | - Valerie Treyer
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
| | - Elisabeth Sartoretti
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
| | - Stephan Waelti
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
- Department of Radiology and Nuclear Medicine, Children's Hospital of Eastern Switzerland, St. Gallen, Switzerland
| | - Moritz Schwyzer
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
- Health Sciences and Technology, Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Gustav K von Schulthess
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
| | - Irene A Burger
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
- Department of Nuclear Medicine, Kantonsspital Baden, Baden, Switzerland
| | - Martin W Huellner
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland
- University of Zurich, Zurich, Switzerland
| | - Michael Messerli
- Department of Nuclear Medicine, University Hospital Zurich, Rämistrasse 100, CH-8091, Zurich, Switzerland.
- University of Zurich, Zurich, Switzerland.
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Bhattarai M, Bache S, Abadi E, Samei E. A systematic task-based image quality assessment of photon-counting and energy integrating CT as a function of reconstruction kernel and phantom size. Med Phys 2024; 51:1047-1060. [PMID: 37469179 PMCID: PMC10796834 DOI: 10.1002/mp.16619] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 04/25/2023] [Accepted: 06/28/2023] [Indexed: 07/21/2023] Open
Abstract
BACKGROUND Image quality of photon-counting and energy integrating CT scanners changes with object size, dose to the object, and kernel selection. PURPOSE To comprehensively compare task-generic image quality of photon-counting CT (PCCT) and energy integrating CT (EICT) systems as a function of phantom size, dose, and reconstruction kernel. METHODS A size-variant phantom (Mercury Phantom 3.0) was used to characterize the image quality of PCCT and EICT systems as a function of object size. The phantom contained five cylinders attached by slanted tapered sections. Each cylinder contained two sections: one uniform for noise, and the other with inserts for spatial resolution and contrast measurements. The phantom was scanned on Siemens' SOMATOM Force and NAEOTOM Alpha at 1.18 and 7.51 mGy without tube current modulation. CTDIvol was matched across two systems by setting the required tube currents, else, all other acquisition settings were fixed. CT sinograms were reconstructed using FBP and iterative (ADMIRE2 - Force; QIR2 - Alpha) algorithms with Body regular (Br) kernels. Noise Power Spectrum (NPS), Task Transfer Function (TTF), contrast-to-noise ratio (CNR), and detectability index (d') for a task of identifying 2-mm disk were evaluated based on AAPM TG-233 metrology using imQuest, an open-source software package. Averaged noise frequency (fav ) and 50% cut-off frequency for TTF (f50 ) were used as scalar metrics to quantify noise texture and spatial resolution, respectively. The difference between image quality metrics' measurements was calculated as IQPCCT - IQEICT . RESULTS From Br40 (soft) to Br64 (sharp), f50 for air insert increased from 0.35 mm-1 ± 0.04 (standard deviation) to 0.76 mm-1 ± 0.17, 0.34 mm-1 ± 0.04 to 0.77 mm-1 ± 0.17, 0.37 mm-1 ± 0.02 to 0.95 mm-1 ± 0.17 for PCCT-T3D-QIR2, PCCT-70keV-QIR2, and EICT-ADMIRE2, respectively, when averaged over all sizes and dose levels. Similarly, from Br40 to Br64, noise magnitude increased from 10.86 HU ± 7.12 to 38.61 HU ± 18.84, 10.94 HU ± 7.08 to 38.82 HU ± 18.70, 13.74 HU ± 11.02 to 52.11 HU ± 26.22 for PCCT-T3D-QIR2, PCCT-70keV-QIR2, and EICT-ADMIRE2, respectively. The difference in fav was consistent across all sizes and dose levels. PCCT-70keV-VMI showed better consistency in contrast measurements for iodine and bone inserts than PCCT-T3D and EICT; however, PCCT-T3D had higher contrast for both inserts. From Br40 to Br64, considering all sizes and dose levels, CNR for iodine insert decreased from 52.30 ± 46.44 to 12.18 ± 10.07, 40.42 ± 33.42 to 9.48 ± 7.16, 39.94 ± 37.60 to 7.84 ± 6.67 for PCCT-T3D-QIR2, PCCT-70keV-QIR2, and EICT-ADMIRE2, respectively. CONCLUSIONS Both PCCT image types, T3D and 70-keV-VMI exhibited similar or better noise, contrast, CNR than EICT when comparing kernels with similar names. For 512 × 512 matrix, PCCT's sharp kernels had lower resolution than EICT's sharp kernels. For all image quality metrics, except extreme low, every dose condition had a similar set of IQ-matching kernels. It suggests that considering patient size and dose level to determine IQ-matching kernel pairs across PCCT and EICT systems may not be imperative while translating protocols, except when the signal to the detector is extremely low.
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Affiliation(s)
- Mridul Bhattarai
- Medical Physics Graduate Program, Duke University, Durham, North Carolina, 27705, USA
- Center for Virtual Imaging Trials (CVIT), Duke University, Durham, North Carolina, 27705, USA
- Department of Radiology – School of Medicine, Duke University, Durham, North Carolina, 27705, USA
| | - Steve Bache
- Clinical Imaging Physics Group – Duke University Health System, Durham, North Carolina, 27705, USA
| | - Ehsan Abadi
- Medical Physics Graduate Program, Duke University, Durham, North Carolina, 27705, USA
- Center for Virtual Imaging Trials (CVIT), Duke University, Durham, North Carolina, 27705, USA
- Department of Radiology – School of Medicine, Duke University, Durham, North Carolina, 27705, USA
| | - Ehsan Samei
- Medical Physics Graduate Program, Duke University, Durham, North Carolina, 27705, USA
- Center for Virtual Imaging Trials (CVIT), Duke University, Durham, North Carolina, 27705, USA
- Department of Radiology – School of Medicine, Duke University, Durham, North Carolina, 27705, USA
- Clinical Imaging Physics Group – Duke University Health System, Durham, North Carolina, 27705, USA
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Patzer TS, Grunz JP, Huflage H, Hennes JL, Pannenbecker P, Gruschwitz P, Afat S, Herrmann J, Bley TA, Kunz AS. Ultra-high resolution photon-counting CT with tin prefiltration for bone-metal interface visualization. Eur J Radiol 2024; 170:111209. [PMID: 37992609 DOI: 10.1016/j.ejrad.2023.111209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 11/08/2023] [Accepted: 11/16/2023] [Indexed: 11/24/2023]
Abstract
PURPOSE To investigate the metal artifact suppression potential of combining tin prefiltration and virtual monoenergetic imaging (VMI) for osseous microarchitecture depiction in ultra-high-resolution (UHR) photon-counting CT (PCCT) of the lower extremity. METHOD Derived from tin-filtered UHR scans at 140 kVp, polychromatic datasets (T3D) and VMI reconstructions at 70, 110, 150, and 190 keV were compared in 117 patients with lower extremity metal implants (53 female; 62.1 ± 18.0 years). Three implant groups were investigated (total arthroplasty [n = 48], osteosynthetic material [n = 43], and external fixation [n = 26]). Image quality was assessed with regions of interest placed in the most pronounced artifacts and adjacent soft tissue, measuring the respective attenuation. Additionally, artifact extent, bone-metal interface interpretability and overall image quality were independently evaluated by three radiologists. RESULTS Artifact reduction was superior with increasing keV level of VMI. While T3D was superior to VMI70keV (p ≥ 0.117), artifacts were more severe in T3D than in VMI ≥ 110 keV (all p ≤ 0.036). Image noise was highest for VMI70keV (all p < 0.001) and lowest for VMI110keV with comparable results for VMI110keV - VMI190keV. Subjective image quality regarding artifacts was superior for VMI ≥ 110 keV (all p ≤ 0.042) and comparable for VMI110keV - VMI190keV. Bone-metal interface interpretability was superior for VMI110keV (all p ≤ 0.001), while T3D, VMI150keV and VMI190keV were comparable. Overall image quality was deemed best for VMI110keV and VMI150keV. Interreader reliability was good in all cases (ICC ≥ 0.833). CONCLUSIONS Tin-filtered UHR-PCCT scans of the lower extremity combined with VMI reconstructions allow for efficient artifact reduction in the vicinity of bone-metal interfaces.
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Affiliation(s)
- Theresa Sophie Patzer
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany.
| | - Jan-Peter Grunz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Henner Huflage
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Jan-Lucca Hennes
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Pauline Pannenbecker
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Philipp Gruschwitz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Saif Afat
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Hoppe-Seyler-Str 3, 72076 Tübingen, Germany
| | - Judith Herrmann
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Hoppe-Seyler-Str 3, 72076 Tübingen, Germany
| | - Thorsten Alexander Bley
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Andreas Steven Kunz
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Hoppe-Seyler-Str 3, 72076 Tübingen, Germany
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Fu C, Zhang B, Guo T, Li J. Imaging Evaluation of Peritoneal Metastasis: Current and Promising Techniques. Korean J Radiol 2024; 25:86-102. [PMID: 38184772 PMCID: PMC10788608 DOI: 10.3348/kjr.2023.0840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 09/28/2023] [Accepted: 10/08/2023] [Indexed: 01/08/2024] Open
Abstract
Early diagnosis, accurate assessment, and localization of peritoneal metastasis (PM) are essential for the selection of appropriate treatments and surgical guidance. However, available imaging modalities (computed tomography [CT], conventional magnetic resonance imaging [MRI], and 18fluorodeoxyglucose positron emission tomography [PET]/CT) have limitations. The advent of new imaging techniques and novel molecular imaging agents have revealed molecular processes in the tumor microenvironment as an application for the early diagnosis and assessment of PM as well as real-time guided surgical resection, which has changed clinical management. In contrast to clinical imaging, which is purely qualitative and subjective for interpreting macroscopic structures, radiomics and artificial intelligence (AI) capitalize on high-dimensional numerical data from images that may reflect tumor pathophysiology. A predictive model can be used to predict the occurrence, recurrence, and prognosis of PM, thereby avoiding unnecessary exploratory surgeries. This review summarizes the role and status of different imaging techniques, especially new imaging strategies such as spectral photon-counting CT, fibroblast activation protein inhibitor (FAPI) PET/CT, near-infrared fluorescence imaging, and PET/MRI, for early diagnosis, assessment of surgical indications, and recurrence monitoring in patients with PM. The clinical applications, limitations, and solutions for fluorescence imaging, radiomics, and AI are also discussed.
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Affiliation(s)
- Chen Fu
- The First School of Clinical Medical, Gansu University of Chinese Medicine, Lanzhou, Gansu, China
| | - Bangxing Zhang
- School of Clinical Medicine, Ningxia Medical University, Yinchuan, Ningxia, China
| | - Tiankang Guo
- Department of General Surgery, Gansu Provincial Hospital, Lanzhou, Gansu, China
- Key Laboratory of Molecular Diagnostics and Precision Medicine for Surgical Oncology in Gansu Province, Gansu Provincial Hospital, Gansu, China
- NHC Key Laboratory of Diagnosis and Therapy of Gastrointestinal Tumor, Gansu Provincial Hospital, Lanzhou, Gansu, China
| | - Junliang Li
- The First School of Clinical Medical, Gansu University of Chinese Medicine, Lanzhou, Gansu, China
- Department of General Surgery, Gansu Provincial Hospital, Lanzhou, Gansu, China
- Key Laboratory of Molecular Diagnostics and Precision Medicine for Surgical Oncology in Gansu Province, Gansu Provincial Hospital, Gansu, China
- NHC Key Laboratory of Diagnosis and Therapy of Gastrointestinal Tumor, Gansu Provincial Hospital, Lanzhou, Gansu, China.
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Hagen F, Soschynski M, Weis M, Hagar MT, Krumm P, Ayx I, Taron J, Krauss T, Hein M, Ruile P, von Zur Muehlen C, Schlett CL, Neubauer J, Tsiflikas I, Russe MF, Arnold P, Faby S, Froelich MF, Weiß J, Stein T, Overhoff D, Bongers M, Nikolaou K, Schönberg SO, Bamberg F, Horger M. Photon-counting computed tomography - clinical application in oncological, cardiovascular, and pediatric radiology. ROFO-FORTSCHR RONTG 2024; 196:25-35. [PMID: 37793417 DOI: 10.1055/a-2119-5802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2023]
Abstract
BACKGROUND Photon-counting detector computed tomography (PCD-CT) is a promising new technology with the potential to fundamentally change workflows in the daily routine and provide new quantitative imaging information to improve clinical decision-making and patient management. METHOD The contents of this review are based on an unrestricted literature search of PubMed and Google Scholar using the search terms "photon-counting CT", "photon-counting detector", "spectral CT", "computed tomography" as well as on the authors' own experience. RESULTS The fundamental difference with respect to the currently established energy-integrating CT detectors is that PCD-CT allows for the counting of every single photon at the detector level. Based on the identified literature, PCD-CT phantom measurements and initial clinical studies have demonstrated that the new technology allows for improved spatial resolution, reduced image noise, and new possibilities for advanced quantitative image postprocessing. CONCLUSION For clinical practice, the potential benefits include fewer beam hardening artifacts, a radiation dose reduction, and the use of new or combinations of contrast agents. In particular, critical patient groups such as oncological, cardiovascular, lung, and head & neck as well as pediatric patient collectives benefit from the clinical advantages. KEY POINTS · Photon-counting computed tomography (PCD-CT) is being used for the first time in routine clinical practice, enabling a significant dose reduction in critical patient populations such as oncology, cardiology, and pediatrics.. · Compared to conventional CT, PCD-CT enables a reduction in electronic image noise.. · Due to the spectral data sets, PCD-CT enables fully comprehensive post-processing applications.. CITATION FORMAT · Hagen F, Soschynski M, Weis M et al. Photon-counting computed tomography - clinical application in oncological, cardiovascular, and pediatric radiology. Fortschr Röntgenstr 2024; 196: 25 - 34.
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Affiliation(s)
- Florian Hagen
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen, Germany
| | - Martin Soschynski
- Department of Diagnostic and Interventional Radiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Meike Weis
- Department of Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Muhammad Taha Hagar
- Department of Diagnostic and Interventional Radiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Patrick Krumm
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen, Germany
| | - Isabelle Ayx
- Department of Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Jana Taron
- Department of Diagnostic and Interventional Radiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Tobias Krauss
- Department of Diagnostic and Interventional Radiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Manuel Hein
- Department of Cardiology & Angiology, University Heart Center Freiburg - Bad Krozingen, University Hospital Freiburg, Faculty of medicine, 79106 Freiburg, Germany
| | - Philipp Ruile
- Department of Cardiology & Angiology, University Heart Center Freiburg - Bad Krozingen, University Hospital Freiburg, Faculty of medicine, 79106 Freiburg, Germany
| | - Constantin von Zur Muehlen
- Department of Cardiology & Angiology, University Heart Center Freiburg - Bad Krozingen, University Hospital Freiburg, Faculty of medicine, 79106 Freiburg, Germany
| | - Christopher L Schlett
- Department of Diagnostic and Interventional Radiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jakob Neubauer
- Department of Diagnostic and Interventional Radiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ilias Tsiflikas
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen, Germany
| | - Maximilian Frederik Russe
- Department of Diagnostic and Interventional Radiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Philipp Arnold
- Department of Diagnostic and Interventional Radiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sebastian Faby
- Computed Tomography, Siemens Healthcare GmbH, Forchheim, Germany
| | - Matthias F Froelich
- Department of Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Jakob Weiß
- Department of Diagnostic and Interventional Radiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Thomas Stein
- Department of Diagnostic and Interventional Radiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Daniel Overhoff
- Department of Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Malte Bongers
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen, Germany
| | - Konstantin Nikolaou
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen, Germany
| | - Stefan O Schönberg
- Department of Radiology and Nuclear Medicine, University Medical Center Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Fabian Bamberg
- Department of Diagnostic and Interventional Radiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Marius Horger
- Department of Diagnostic and Interventional Radiology, University Hospital Tübingen, Tübingen, Germany
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Skawran S, Sartoretti T, Gennari AG, Schwyzer M, Sartoretti E, Treyer V, Maurer A, Huellner MW, Waelti S, Messerli M. Evolution of CT radiation dose in pediatric patients undergoing hybrid 2-[ 18F]FDG PET/CT between 2007 and 2021. Br J Radiol 2023; 96:20220482. [PMID: 37751216 PMCID: PMC10646648 DOI: 10.1259/bjr.20220482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 09/16/2023] [Accepted: 09/20/2023] [Indexed: 09/27/2023] Open
Abstract
OBJECTIVES To evaluate the evolution of CT radiation dose in pediatric patients undergoing hybrid 2-[18F]fluoro-2-deoxy-D-glucose (2-[18F]FDG) PET/CT between 2007 and 2021. METHODS AND MATERIALS Data from all pediatric patients aged 0-18 years who underwent hybrid 2-[18F]FDG PET/CT of the body between January 2007 and May 2021 were reviewed. Demographic and imaging parameters were collected. A board-certified radiologist reviewed all CT scans and measured image noise in the brain, liver, and adductor muscles. RESULTS 294 scans from 167 children (72 females (43%); median age: 14 (IQR 10-15) years; BMI: median 17.5 (IQR 15-20.4) kg/m2) were included. CT dose index-volume (CTDIvol) and dose length product (DLP) both decreased significantly from 2007 to 2021 (both p < 0.001, Spearman's rho coefficients -0.46 and -0.35, respectively). Specifically, from 2007 to 2009 to 2019-2021 CTDIvol and DLP decreased from 2.94 (2.14-2.99) mGy and 309 (230-371) mGy*cm, respectively, to 0.855 (0.568-1.11) mGy and 108 (65.6-207) mGy*cm, respectively. From 2007 to 2021, image noise in the brain and liver remained constant (p = 0.26 and p = 0.06), while it decreased in the adductor muscles (p = 0.007). Peak tube voltage selection (in kilovolt, kV) of CT scans shifted from high kV imaging (140 or 120kVp) to low kV imaging (100 or 80kVp) (p < 0.001) from 2007 to 2021. CONCLUSION CT radiation dose in pediatric patients undergoing hybrid 2-[18F]FDG PET/CT has decreased in recent years equaling approximately one-third of the initial amount. ADVANCES IN KNOWLEDGE Over the past 15 years, CT radiation dose decreased considerably in pediatric patients undergoing hybrid imaging, while objective image quality may not have been compromised.
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Srinivas-Rao S, Cao J, Marin D, Kambadakone A. Dual-Energy Computed Tomography to Photon Counting Computed Tomography: Emerging Technological Innovations. Radiol Clin North Am 2023; 61:933-944. [PMID: 37758361 DOI: 10.1016/j.rcl.2023.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Computed tomography (CT) has seen remarkable developments in the past several decades, radically transforming the role of imaging in day-to-day clinical practice. Dual-energy CT (DECT), an exciting innovation introduced in the early part of this century, has widened the scope of CT, opening new opportunities due to its ability to provide superior tissue characterization. The introduction of photon-counting CT (PCCT) heralds a paradigm shift in CT scanner technology representing another significant milestone in CT innovation. PCCT offers several advantages over DECT, such as improved spectral resolution, enhanced tissue characterization, reduced image artifacts, and improved image quality.
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Affiliation(s)
- Shravya Srinivas-Rao
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, White 270, Boston, MA 02114-2696, USA
| | - Jinjin Cao
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, White 270, Boston, MA 02114-2696, USA
| | - Daniele Marin
- Department of Radiology, Duke University Medical Center, Box 3808 Erwin Road, Durham, NC 27710, USA
| | - Avinash Kambadakone
- Department of Radiology, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, White 270, Boston, MA 02114-2696, USA.
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Bhattarai M, Bache S, Abadi E, Samei E. Exploration of the pulse pileup effects in a clinical CdTe-based photon-counting computed tomography. Med Phys 2023; 50:6693-6703. [PMID: 37602816 PMCID: PMC10840699 DOI: 10.1002/mp.16671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 06/27/2023] [Accepted: 07/20/2023] [Indexed: 08/22/2023] Open
Abstract
BACKGROUND High tube current generates a high flux of x-rays to photon counting detectors (PCDs) that can potentially result in the piling up of pulses formed by concurrent photons, which can cause count loss and energy resolution degradation. PURPOSE To evaluate the performance of clinical photon-counting CT (PCCT) systems in high flux, potentially influenced by pulse pileup effects, in terms of task-generic image quality metrics. METHODS A clinical phantom was scanned on a commercial PCCT scanner (NAEOTOM Alpha, Siemens) at 120 kV under fourteen different tube current levels (40-1000 mA) with a rotation time of 0.25 s and a pitch of 1. The dose levels corresponded to CTDIvol (32 cm phantom) of 0.79-19.8 mGy. CT sinograms were reconstructed using QIR-off mode (noniterative reconstruction algorithm), Br44 kernel, and a voxel size of0.4102 × 0.4102 × 3 mm 3 $0.4102 \times 0.4102 \times 3{\mathrm{\ mm}}^3$ . imQuest, an open-source MATLAB-based software package was used to calculate noise power spectrum (NPS), task transfer function (TTF), contrast-to-noise ratio (CNR), and CT number according to AAPM Task Group 233 metrology. RESULTS The 50% cut-off frequency of TTF (f50 ) remained mostly constant across all higher tube currents for all inserts, namely polyethylene, bone, air, and acrylic. Using the lowest two data points (40 and 80 mA), the expected relationship between noise magnitude and tube current was determined to be noise∝ $ \propto \ $ mA-0.47 . The measured noise magnitude were up to 11.1% higher than the expected value at the highest tube current. The average frequency of NPS (fav ) decreased from 0.32 to 0.29 mm-1 as tube current increased from 40 to 1000 mA. No considerable effects were observed in CT number measurement of any insert; however, CT numbers for air and bone changed almost monotonically as tube current increased. Absolute CNR increased monotonically for all inserts; however, the difference between measured and expected CNRs were approximately -6% to 12% across all tube currents. CONCLUSIONS Increasing tube currents did not affect the spatial resolution, but slightly affected the CT number and noise measurements of the clinical PCCT system. However, the effects were only considerable at clinically irrelevant tube currents used on a small 20-cm phantom. In general clinical practices, automatic exposure control techniques are used to decrease the variation of flux on the detector, which alleviates the chances of detector saturation due to high count rates. The observed effects could be due to pulse pileup, signal-dependent filtration of the system, or nonlinearities in the reconstruction algorithm. In conclusion, either the deadtime of the detector used in the photon-counting CT system is shorter such that count losses due to pulse pileup are negligible, or pulse pileup has inconsiderable effects on the image quality of clinical photon-counting CT systems in routine clinical practice due to possible corrections applied on the system.
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Affiliation(s)
- Mridul Bhattarai
- Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
- Center for Virtual Imaging Trials (CVIT), Duke University, Durham, North Carolina, USA
- Department of Radiology - School of Medicine, Duke University, Durham, North Carolina, USA
| | - Steve Bache
- Clinical Imaging Physics Group - Duke University Health System, Durham, North Carolina, USA
| | - Ehsan Abadi
- Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
- Center for Virtual Imaging Trials (CVIT), Duke University, Durham, North Carolina, USA
- Department of Radiology - School of Medicine, Duke University, Durham, North Carolina, USA
| | - Ehsan Samei
- Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA
- Center for Virtual Imaging Trials (CVIT), Duke University, Durham, North Carolina, USA
- Department of Radiology - School of Medicine, Duke University, Durham, North Carolina, USA
- Clinical Imaging Physics Group - Duke University Health System, Durham, North Carolina, USA
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Turrion Gomollon AM, Mergen V, Sartoretti T, Polacin M, Nakhostin D, Puippe G, Alkadhi H, Euler A. Photon-Counting Detector CT Angiography for Endoleak Detection After Endovascular Aortic Repair: Triphasic CT With True Noncontrast Versus Biphasic CT With Virtual Noniodine Imaging. Invest Radiol 2023; 58:816-821. [PMID: 37358359 PMCID: PMC10581441 DOI: 10.1097/rli.0000000000000993] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 04/25/2023] [Indexed: 06/27/2023]
Abstract
OBJECTIVES The aim of this study was to compare image quality and endoleak detection after endovascular abdominal aortic aneurysm repair between a triphasic computed tomography (CT) with true noncontrast (TNC) and a biphasic CT with virtual noniodine (VNI) images on photon-counting detector CT (PCD-CT). MATERIALS AND METHODS Adult patients after endovascular abdominal aortic aneurysm repair who received a triphasic examination (TNC, arterial, venous phase) on a PCD-CT between August 2021 and July 2022 were retrospectively included. Endoleak detection was evaluated by 2 blinded radiologists on 2 different readout sets (triphasic CT with TNC-arterial-venous vs biphasic CT with VNI-arterial-venous). Virtual noniodine images were reconstructed from the venous phase. The radiologic report with additional confirmation by an expert reader served as reference standard for endoleak presence. Sensitivity, specificity, and interreader agreement (Krippendorf α) were calculated. Image noise was assessed subjectively in patients using a 5-point scale and objectively calculating the noise power spectrum in a phantom. RESULTS One hundred ten patients (7 women; age, 76 ± 8 years) with 41 endoleaks were included. Endoleak detection was comparable between both readout sets with a sensitivity and specificity of 0.95/0.84 (TNC) versus 0.95/0.86 (VNI) for reader 1 and 0.88/0.98 (TNC) versus 0.88/0.94 (VNI) for reader 2. Interreader agreement for endoleak detection was substantial (TNC: 0.716, VNI: 0.756). Subjective image noise was comparable between TNC and VNI (4; IQR [4, 5] vs 4; IQR [4, 5], P = 0.44). In the phantom, noise power spectrum peak spatial frequency was similar between TNC and VNI (both f peak = 0.16 mm -1 ). Objective image noise was higher in TNC (12.7 HU) as compared with VNI (11.5 HU). CONCLUSIONS Endoleak detection and image quality were comparable using VNI images in biphasic CT as compared with TNC images in triphasic CT offering the possibility to reduce scan phases and radiation exposure.
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Farhadi F, Sahbaee P, Rajagopal JR, Nikpanah M, Saboury B, Gutjahr R, Biassou NM, Shah R, Flohr TG, Samei E, Pritchard WF, Malayeri AA, Bluemke DA, Jones EC. Virtual monoenergetic imaging in photon-counting CT of the head and neck. Clin Imaging 2023; 102:109-115. [PMID: 37672849 PMCID: PMC10838526 DOI: 10.1016/j.clinimag.2023.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 08/08/2023] [Indexed: 09/08/2023]
Abstract
PURPOSE Advantages of virtual monoenergetic images (VMI) have been reported for dual energy CT of the head and neck, and more recently VMIs derived from photon-counting (PCCT) angiography of the head and neck. We report image quality metrics of VMI in a PCCT angiography dataset, expanding the anatomical regions evaluated and extending observer-based qualitative methods further than previously reported. METHODS In a prospective study, asymptomatic subjects underwent contrast enhanced PCCT of the head and neck using an investigational scanner. Image sets of low, high, and full spectrum (Threshold-1) energies; linear mix of low and high energies (Mix); and 23 VMIs (40-150 keV, 5 keV increments) were generated. In 8 anatomical locations, SNR and radiologists' preferences for VMI energy levels were measured using a forced-choice rank method (4 observers) and ratings of image quality using visual grading characteristic (VGC) analysis (2 observers) comparing VMI to Mix and Threshold-1 images. RESULTS Fifteen subjects were included (7 men, 8 women, mean 57 years, range 46-75). Among all VMIs, SNRs varied by anatomic location. The highest SNRs were observed in VMIs. Radiologists preferred 50-60 keV VMIs for vascular structures and 75-85 keV for all other structures. Cumulative ratings of image quality averaged across all locations were higher for VMIs with areas under the curve of VMI vs Mix and VMI vs Threshold-1 of 0.67 and 0.68 for the first reader and 0.72 and 0.76 for the second, respectively. CONCLUSION Preferred keV level and quality ratings of VMI compared to mixed and Threshold-1 images varied by anatomical location.
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Affiliation(s)
- Faraz Farhadi
- Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | | | - Jayasai R Rajagopal
- Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD, USA; Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Moozhan Nikpanah
- Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | - Babak Saboury
- Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | | | - Nadia M Biassou
- Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | - Ritu Shah
- Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | | | - Ehsan Samei
- Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - William F Pritchard
- Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD, USA; Center for Interventional Oncology, Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | - Ashkan A Malayeri
- Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD, USA
| | - David A Bluemke
- Department of Radiology, University of Wisconsin, Madison, WI, USA
| | - Elizabeth C Jones
- Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Bethesda, MD, USA.
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Wu Y, Ye Z, Chen J, Deng L, Song B. Photon Counting CT: Technical Principles, Clinical Applications, and Future Prospects. Acad Radiol 2023; 30:2362-2382. [PMID: 37369618 DOI: 10.1016/j.acra.2023.05.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 05/27/2023] [Accepted: 05/28/2023] [Indexed: 06/29/2023]
Abstract
Photon-counting computed tomography (PCCT) is a new technique that utilizes photon-counting detectors to convert individual X-ray photons directly into an electrical signal, which can achieve higher spatial resolution, improved iodine signal, radiation dose reduction, artifact reduction, and multienergy imaging. This review introduces the technical principles of PCCT, and summarizes its first-in-human experience and current applications in clinical settings, and discusses the future prospects of PCCT.
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Affiliation(s)
- Yingyi Wu
- Department of Radiology, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu 610041, China (Y.Y.W., Z.Y., J.C., L.P.D., B.S.)
| | - Zheng Ye
- Department of Radiology, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu 610041, China (Y.Y.W., Z.Y., J.C., L.P.D., B.S.)
| | - Jie Chen
- Department of Radiology, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu 610041, China (Y.Y.W., Z.Y., J.C., L.P.D., B.S.)
| | - Liping Deng
- Department of Radiology, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu 610041, China (Y.Y.W., Z.Y., J.C., L.P.D., B.S.)
| | - Bin Song
- Department of Radiology, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu 610041, China (Y.Y.W., Z.Y., J.C., L.P.D., B.S.); Department of Radiology, Sanya People' s Hospital, Sanya, Hainan, China (B.S.).
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28
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Graafen D, Müller L, Halfmann MC, Stoehr F, Foerster F, Düber C, Yang Y, Emrich T, Kloeckner R. Soft Reconstruction Kernels Improve HCC Imaging on a Photon-Counting Detector CT. Acad Radiol 2023; 30 Suppl 1:S143-S154. [PMID: 37095047 DOI: 10.1016/j.acra.2023.03.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Revised: 03/08/2023] [Accepted: 03/20/2023] [Indexed: 04/26/2023]
Abstract
RATIONALE AND OBJECTIVES Hepatocellular carcinoma (HCC) is the only tumor entity that allows non-invasive diagnosis based on imaging without further histological proof. Therefore, excellent image quality is of utmost importance for HCC diagnosis. Novel photon-counting detector (PCD) CT improves image quality via noise reduction and higher spatial resolution, inherently providing spectral information. The aim of this study was to investigate these improvements for HCC imaging with triple-phase liver PCD-CT in a phantom and patient population study focusing on identification of the optimal reconstruction kernel. MATERIALS AND METHODS Phantom experiments were performed to analyze objective quality characteristics of the regular body and quantitative reconstruction kernels, each with four sharpness levels (36-40-44-48). For 24 patients with viable HCC lesions on PCD-CT, virtual monoenergetic images at 50 keV were reconstructed using these kernels. Quantitative image analysis included contrast-to-noise ratio (CNR) and edge sharpness. Three raters performed qualitative analyses evaluating noise, contrast, lesion conspicuity, and overall image quality. RESULTS In all contrast phases, the CNR was highest using the kernels with a sharpness level of 36 (all p < 0.05), with no significant influence on lesion sharpness. Softer reconstruction kernels were also rated better regarding noise and image quality (all p < 0.05). No significant differences were found in image contrast and lesion conspicuity. Comparing body and quantitative kernels with equal sharpness levels, there was no difference in image quality criteria, neither regarding in vitro nor in vivo analysis. CONCLUSION Soft reconstruction kernels yield the best overall quality for the evaluation of HCC in PCD-CT. As the image quality of quantitative kernels with potential for spectral post-processing is not restricted compared to regular body kernels, they should be preferred.
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Affiliation(s)
- D Graafen
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany (D.G., L.M., M.C.H., F.S., C.D., Y.Y., T.E., R.K.).
| | - L Müller
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany (D.G., L.M., M.C.H., F.S., C.D., Y.Y., T.E., R.K.)
| | - M C Halfmann
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany (D.G., L.M., M.C.H., F.S., C.D., Y.Y., T.E., R.K.); German Center for Cardiovascular Research (DZHK), Partner-Site Rhine-Main, Mainz, Germany (M.C.H., T.E.)
| | - F Stoehr
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany (D.G., L.M., M.C.H., F.S., C.D., Y.Y., T.E., R.K.)
| | - F Foerster
- Department of Medicine I, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany (F.F.)
| | - C Düber
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany (D.G., L.M., M.C.H., F.S., C.D., Y.Y., T.E., R.K.)
| | - Y Yang
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany (D.G., L.M., M.C.H., F.S., C.D., Y.Y., T.E., R.K.)
| | - T Emrich
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany (D.G., L.M., M.C.H., F.S., C.D., Y.Y., T.E., R.K.); German Center for Cardiovascular Research (DZHK), Partner-Site Rhine-Main, Mainz, Germany (M.C.H., T.E.); Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC (T.E.)
| | - R Kloeckner
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany (D.G., L.M., M.C.H., F.S., C.D., Y.Y., T.E., R.K.)
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Schade KA, Mergen V, Sartoretti T, Alkadhi H, Euler A. Pseudoenhancement in Cystic Renal Lesions - Impact of Virtual Monoenergetic Images of Photon-Counting Detector CT on Lesion Classification. Acad Radiol 2023; 30 Suppl 1:S305-S313. [PMID: 37150736 DOI: 10.1016/j.acra.2023.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 03/30/2023] [Accepted: 04/03/2023] [Indexed: 05/09/2023]
Abstract
RATIONALE AND OBJECTIVES To investigate the impact of virtual monoenergetic images (VMI) from photon-counting detector CT (PCD-CT) on the enhancement and classification of renal cysts. MATERIALS AND METHODS Adults with renal cysts (≥7 mm) who received a triphasic examination on a clinical PCD-CT (120 kVp; IQ level 68) between July 2021 and March 2022 were retrospectively identified. Only non-enhancing cysts (enhancement<10 HU between unenhanced and venous phase at 70 keV) were included. VMI from 40 to 190 keV with increments of 10 keV were reconstructed from the venous phase. Enhancement was measured to classify each lesion as non-enhancing (<10 HU), equivocally enhancing (10-19 HU), and definitely enhancing (≥20 HU). Classification changes as a function of VMI were assessed. Pearson correlation coefficient, the Kruskal-Wallis and the Chi-square test were used. RESULTS A total of 86 patients (mean age, 74 ± 9 years; 74 male) with 160 non-enhancing renal cysts (17.6 ± 10 mm) were included. CT attenuation of the cysts increased from higher to lower VMI levels with a mean attenuation of 4 ± 11 HU at 190 keV to 36 ± 17 HU at 40 keV. Mean attenuation of the renal parenchyma was 43 ± 4 HU at 190 keV and 414 ± 71 HU at 40 keV. No cyst exhibited enhancement from 70 keV to 190 keV. At 40, 50, and 60 keV, 35% (56/160), 29% (47/160) and 9% (15/160) of cysts showed equivocal and 46% (74/160), 10% (16/160), and 0% (0/160) definite enhancement, respectively. There was no significant influence of size (P=.13), cyst location (P=.9) and BMI (P=.19) on enhancement classification. CONCLUSION VMI has a relevant impact on enhancement and classification of renal cysts with misclassification in a large number of cases at energy levels below 70 keV.
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Affiliation(s)
- Katharina Alexandra Schade
- Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland (K.A.S., V.M., T.S., H.A., A.E.)
| | - Victor Mergen
- Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland (K.A.S., V.M., T.S., H.A., A.E.)
| | - Thomas Sartoretti
- Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland (K.A.S., V.M., T.S., H.A., A.E.)
| | - Hatem Alkadhi
- Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland (K.A.S., V.M., T.S., H.A., A.E.)
| | - André Euler
- Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland (K.A.S., V.M., T.S., H.A., A.E.); Institute of Radiology, Kantonsspital Baden, Baden, Switzerland (A.E.).
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Vrbaski S, Bache S, Rajagopal J, Samei E. Quantitative performance of photon-counting CT at low dose: Virtual monochromatic imaging and iodine quantification. Med Phys 2023; 50:5421-5433. [PMID: 37415402 PMCID: PMC10897956 DOI: 10.1002/mp.16583] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 06/11/2023] [Accepted: 06/12/2023] [Indexed: 07/08/2023] Open
Abstract
BACKGROUND Quantitative imaging techniques, such as virtual monochromatic imaging (VMI) and iodine quantification (IQ), have proven valuable diagnostic methods in several specific clinical tasks such as tumor and tissue differentiation. Recently, a new generation of computed tomography (CT) scanners equipped with photon-counting detectors (PCD) has reached clinical status. PURPOSE This work aimed to investigate the performance of a new photon-counting CT (PC-CT) in low-dose quantitative imaging tasks, comparing it to an earlier generation CT scanner with an energy-integrating detector dual-energy CT (DE-CT). The accuracy and precision of the quantification across size, dose, material types (including low and high iodine concentrations), displacement from iso-center, and solvent (tissue background) composition were explored. METHODS Quantitative analysis was performed on two clinical scanners, Siemens SOMATOM Force and NAEOTOM Alpha using a multi-energy phantom with plastic inserts mimicking different iodine concentrations and tissue types. The tube configurations in the dual-energy scanner were 80/150Sn kVp and 100/150Sn kVp, while for PC-CT both tube voltages were set to either 120 or 140 kVp with photon-counting energy thresholds set at 20/65 or 20/70 keV. The statistical significance of patient-related parameters in quantitative measurements was examined using ANOVA and pairwise comparison with the posthoc Tukey honest significance test. Scanner bias was assessed in both quantitative tasks for relevant patient-specific parameters. RESULTS The accuracy of IQ and VMI in the PC-CT was comparable between standard and low radiation doses (p < 0.01). The patient size and tissue type significantly affect the accuracy of both quantitative imaging tasks in both scanners. The PC-CT scanner outperforms the DE-CT scanner in the IQ task in all cases. Iodine quantification bias in the PC-CT (-0.9 ± 0.15 mg/mL) at low doses in our study was comparable to that of DE-CT (range -2.6 to 1.5 mg/mL, published elsewhere) at a 1.7× higher dose, but the dose reduction severely biased DE-CT (4.72 ± 0.22 mg/mL). The accuracy in Hounsfield units (HU) estimation was comparable for 70 and 100 keV virtual imaging between scanners, but PC-CT was significantly underestimating virtual 40 keV HU values of dense materials in the phantom representing the extremely obese population. CONCLUSIONS The statistical analysis of our measurements reveals better IQ at lower radiation doses using new PC-CT. Although VMI performance was mostly comparable between the scanners, the DE-CT scanner quantitatively outperformed PC-CT when estimating HU values in the specific case of very large phantoms and dense materials, benefiting from increased X-ray tube potentials.
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Affiliation(s)
- Stevan Vrbaski
- Department of Radiology, Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina, USA
- Department of Physics, University of Trieste, Trieste, Italy
- Elettra-Sincrotrone Trieste, Basovizza, Trieste, Italy
| | - Steve Bache
- Clinical Imaging Physics Group, Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Jayasai Rajagopal
- Department of Radiology, Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina, USA
- Radiology and Imaging Sciences,Clinical Center, National Institutes of Health, Bethesda, Maryland, USA
| | - Ehsan Samei
- Department of Radiology, Carl E. Ravin Advanced Imaging Laboratories, Duke University Medical Center, Durham, North Carolina, USA
- Clinical Imaging Physics Group, Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA
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Bache ST, Samei E. A methodology for incorporating a photon-counting CT system into routine clinical use. J Appl Clin Med Phys 2023; 24:e14069. [PMID: 37389963 PMCID: PMC10402682 DOI: 10.1002/acm2.14069] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 04/24/2023] [Accepted: 05/22/2023] [Indexed: 07/02/2023] Open
Abstract
Photon-counting computed tomography (PCCT) systems are increasingly available in the U.S. following Food and Drug Administration (FDA) approval of the first clinical PCCT system in Fall 2021. Consequently, there will be a need to incorporate PCCTs into existing fleets of traditional CT systems. The commissioning process of a PCCT was devised by evaluating the degree of agreement between the performance of the PCCT and that of established clinical CT systems. A PCCT system (Siemens NAEOTOM Alpha) was evaluated using the American College of Radiology(ACR) CT phantom (Gammex 464). The phantom was scanned on the system and on a 3rd Generation EID CT system (Siemens Force) at three clinical dose levels. Images were reconstructed across the range of available reconstruction kernels and Iterative Reconstruction (IR) strengths. Two image quality metrics-spatial resolution and noise texture-were calculated using AAPM TG233 software (imQuest), as well as a dose metric to achieve target image noise magnitude of 10 HU. For each pair of EID-PCCT kernel/IR strengths, the difference in metrics were calculated, weighted, and multiplied over all metrics to determine the concordance between systems. IR performance was characterized by comparing relative noise texture and reference dose as a function of IR strength for each system. In general, as kernel "sharpness" increased for each system, spatial resolution, noise spatial frequency, and reference dose increased. For a given kernel, EID reconstruction showed higher spatial resolution compared to PCCT in standard resolution mode. PCCT implementation of IR better preserved noise texture across all strengths compared to the EID, demonstrated by respective 20 and 7% shifts in noise texture from IR "Off" to IR "Max." Overall, the closest match for a given EID reconstruction kernel/IR strength was identified as a PCCT kernel with "sharpness" increased by 1 step and IR strength increased by 1-2 steps. Substantial dose reduction potential of up to 70% was found when targeting a constant noise magnitude.
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Affiliation(s)
- Steven T. Bache
- Department of Radiology Clinical Imaging Physics GroupDuke University Medical CenterDurhamNorth CarolinaUSA
| | - Ehsan Samei
- Carl E. Ravin Advanced Imaging LaboratoriesDuke University Medical CenterDurhamNorth CarolinaUSA
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Graafen D, Stoehr F, Halfmann MC, Emrich T, Foerster F, Yang Y, Düber C, Müller L, Kloeckner R. Quantum iterative reconstruction on a photon-counting detector CT improves the quality of hepatocellular carcinoma imaging. Cancer Imaging 2023; 23:69. [PMID: 37480062 PMCID: PMC10362630 DOI: 10.1186/s40644-023-00592-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 07/08/2023] [Indexed: 07/23/2023] Open
Abstract
BACKGROUND Excellent image quality is crucial for workup of hepatocellular carcinoma (HCC) in patients with liver cirrhosis because a signature tumor signal allows for non-invasive diagnosis without histologic proof. Photon-counting detector computed tomography (PCD-CT) can enhance abdominal image quality, especially in combination with a novel iterative reconstruction algorithm, quantum iterative reconstruction (QIR). The purpose of this study was to analyze the impact of different QIR levels on PCD-CT imaging of HCC in both phantom and patient scans. METHODS Virtual monoenergetic images at 50 keV were reconstructed using filtered back projection and all available QIR levels (QIR 1-4). Objective image quality properties were investigated in phantom experiments. The study also included 44 patients with triple-phase liver PCD-CT scans of viable HCC lesions. Quantitative image analysis involved assessing the noise, contrast, and contrast-to-noise ratio of the lesions. Qualitative image analysis was performed by three raters evaluating noise, artifacts, lesion conspicuity, and overall image quality using a 5-point Likert scale. RESULTS Noise power spectra in the phantom experiments showed increasing noise suppression with higher QIR levels without affecting the modulation transfer function. This pattern was confirmed in the in vivo scans, in which the lowest noise levels were found in QIR-4 reconstructions, with around a 50% reduction in median noise level compared with the filtered back projection images. As contrast does not change with QIR, QIR-4 also yielded the highest contrast-to-noise ratios. With increasing QIR levels, rater scores were significantly better for all qualitative image criteria (all p < .05). CONCLUSIONS Without compromising image sharpness, the best image quality of iodine contrast optimized low-keV virtual monoenergetic images can be achieved using the highest QIR level to suppress noise. Using these settings as standard reconstruction for HCC in PCD-CT imaging might improve diagnostic accuracy and confidence.
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Affiliation(s)
- Dirk Graafen
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany.
| | - Fabian Stoehr
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Moritz C Halfmann
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
- German Center for Cardiovascular Research (DZHK), Partner-Site Rhine-Main, Mainz, Germany
| | - Tilman Emrich
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
- German Center for Cardiovascular Research (DZHK), Partner-Site Rhine-Main, Mainz, Germany
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
| | - Friedrich Foerster
- Department of Medicine I, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Yang Yang
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Christoph Düber
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Lukas Müller
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
| | - Roman Kloeckner
- Diagnostic and Interventional Radiology, University Medical Center of the Johannes Gutenberg-University Mainz, Mainz, Germany
- Present Address: Institute of Interventional Radiology, University Hospital Schleswig-Holstein, Campus Lübeck, Lübeck, Germany
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Abstract
ABSTRACT Noninvasive vascular imaging with computed tomography (CT) has become the clinical mainstay for many indications and body regions. The recent introduction of photon-counting detector (PCD)-CT into clinical routine has further broadened the spectrum of vascular applications. Technical improvements of PCD-CT, such as the decreased noise levels, improved contrast-to-noise ratio, and full spectral multienergy data information from every acquisition, have the potential to further impact on clinical decision making and ultimately on outcome of vascular patients. Early experience with the new PCD-CT technology demonstrates these improvements in various aspects. This review summarizes the main advantages of PCD-CT for vascular imaging a discussion of the PureLumen and PureCalcium algorithms.
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Affiliation(s)
| | - Hatem Alkadhi
- Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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Schwartz FR, Samei E, Marin D. Exploiting the Potential of Photon-Counting CT in Abdominal Imaging. Invest Radiol 2023; 58:488-498. [PMID: 36728045 DOI: 10.1097/rli.0000000000000949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
ABSTRACT Photon-counting computed tomography (PCCT) imaging uses a new detector technology to provide added information beyond what can already be obtained with current CT and MR technologies. This review provides an overview of PCCT of the abdomen and focuses specifically on applications that benefit the most from this new imaging technique. We describe the requirements for a successful abdominal PCCT acquisition and the challenges for clinical translation. The review highlights work done within the last year with an emphasis on new protocols that have been tested in clinical practice. Applications of PCCT include imaging of cystic lesions, sources of bleeding, and cancers. Photon-counting CT is positioned to move beyond detection of disease to better quantitative staging of disease and measurement of treatment response.
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Affiliation(s)
| | - Ehsan Samei
- Quantitative Imaging and Analysis Lab, Duke University Health System, Durham, NC
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Wrazidlo R, Walder L, Estler A, Gutjahr R, Schmidt B, Faby S, Fritz J, Nikolaou K, Horger M, Hagen F. Radiation Dose Reduction in Contrast-Enhanced Abdominal CT: Comparison of Photon-Counting Detector CT with 2nd Generation Dual-Source Dual-Energy CT in an oncologic cohort. Acad Radiol 2023; 30:855-862. [PMID: 35760710 DOI: 10.1016/j.acra.2022.05.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 05/30/2022] [Accepted: 05/30/2022] [Indexed: 11/28/2022]
Abstract
RATIONAL AND OBJECTIVES Comparison of radiation dose and image quality in routine abdominal and pelvic contrast-enhanced computed tomography (CECT) between a photon-counting detector CT (PCD-CT) and a dual energy dual source CT (DSCT). MATERIALS AND METHODS 70 oncologic patients (mean age 66 ± 12 years, 29 females) were prospectively enrolled between November 2021 and February 2022. Abdominal CECT were clinically indicated and performed first on a 2nd-generation DSCT and at follow-up on a 1st-generation dual-source PCD-CT. The same contrast media (Imeron 350, Bracco imaging) and pump protocol was used for both scans. For both scanners, polychromatic images were reconstructed with 3mm slice thickness and comparable kernel (I30f[DSCT] and Br40f[PCD-CT]); for PCD-CT data from all counted events above the lowest energy threshold at 20 keV ("T3D") were used. Results were compared in terms of radiation dose metrics of CT dose index (CTDIvol), dose length product (DLP) and size-specific dose estimation (SSDE), objective and subjective measurements of image quality were scored by two emergency radiologists including lesion conspicuity. RESULTS Median time interval between the scans was 4 months (IQR: 3-6). CNRvessel and SNRvessel of T3D reconstructions from PCD-CT were significantly higher than those of DSCT (all, p < 0.05). Qualitative image noise analysis from PCD-CT and DSCT yielded a mean of 4 each. Lesion conspicuity was rated significantly higher in PCD-CT (Q3 strength) compared to DSCT images. CTDI, DLP and SSDE mean values for PCD-CT and DSCT were 7.98 ± 2.56 mGy vs. 14.11 ± 2.92 mGy, 393.13 ± 153.55 mGy*cm vs. 693.61 ± 185.76 mGy*cm and 9.98 ± 2.41 vs. 14.63 ± 1.63, respectively, translating to a dose reduction of around 32% (SSDE). CONCLUSION PCD-CT enables oncologic abdominal CT with a significantly reduced dose while keeping image quality similar to 2nd-generation DSCT.
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Affiliation(s)
- Robin Wrazidlo
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Lukas Walder
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Arne Estler
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Ralf Gutjahr
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Bernhard Schmidt
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Sebastian Faby
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Jan Fritz
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Konstantin Nikolaou
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
| | - Marius Horger
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.).
| | - Florian Hagen
- Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, 72076 Tübingen, Germany (R.W., L.W., A.E., K.N., M.H., F.H.); Siemens Healthcare GmbH, 91052 Erlangen, Germany (R.G., B.S., S.F.); NYU Grossman School of Medicine, Department of Radiology, New York, NY 10016, USA (J.F.)
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Fink N, Zsarnoczay E, Schoepf UJ, O'Doherty J, Griffith JP, Pinos D, Tesche C, Ricke J, Willemink MJ, Varga-Szemes A, Emrich T. Radiation Dose Reduction for Coronary Artery Calcium Scoring Using a Virtual Noniodine Algorithm on Photon-Counting Detector Computed-Tomography Phantom Data. Diagnostics (Basel) 2023; 13:diagnostics13091540. [PMID: 37174932 PMCID: PMC10177425 DOI: 10.3390/diagnostics13091540] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 04/14/2023] [Accepted: 04/24/2023] [Indexed: 05/15/2023] Open
Abstract
Background: On the basis of the hypothesis that virtual noniodine (VNI)-based coronary artery calcium scoring (CACS) is feasible at reduced radiation doses, this study assesses the impact of radiation dose reduction on the accuracy of this VNI algorithm on a photon-counting detector (PCD)-CT. Methods: In a systematic in vitro setting, a phantom for CACS simulating three chest sizes was scanned on a clinical PCD-CT. The standard radiation dose was chosen at volumetric CT dose indices (CTDIVol) of 1.5, 3.3, 7.0 mGy for small, medium-sized, and large phantoms, and was gradually reduced by adjusting the tube current resulting in 100, 75, 50, and 25%, respectively. VNI images were reconstructed at 55 keV, quantum iterative reconstruction (QIR)1, and at 60 keV/QIR4, and evaluated regarding image quality (image noise (IN), contrast-to-noise ratio (CNR)), and CACS. All VNI results were compared to true noncontrast (TNC)-based CACS at 70 keV and standard radiation dose (reference). Results: INTNC was significantly higher than INVNI, and INVNI at 55 keV/QIR1 higher than at 60 keV/QIR4 (100% dose: 16.7 ± 1.9 vs. 12.8 ± 1.7 vs. 7.7 ± 0.9; p < 0.001 for every radiation dose). CNRTNC was higher than CNRVNI, but it was better to use 60 keV/QIR4 (p < 0.001). CACSVNI showed strong correlation and agreement at every radiation dose (p < 0.001, r > 0.9, intraclass correlation coefficient > 0.9). The coefficients of the variation in root-mean squared error were less than 10% and thus clinically nonrelevant for the CACSVNI of every radiation dose. Conclusion: This phantom study suggests that CACSVNI is feasible on PCD-CT, even at reduced radiation dose while maintaining image quality and CACS accuracy.
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Affiliation(s)
- Nicola Fink
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
- Department of Radiology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Emese Zsarnoczay
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
- Medical Imaging Center, Semmelweis University, Korányi Sándor utca 2, 1083 Budapest, Hungary
| | - U Joseph Schoepf
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
| | - Jim O'Doherty
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
- Siemens Medical Solutions, 40 Liberty Boulevard, Malvern, PA 19355, USA
| | - Joseph P Griffith
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
| | - Daniel Pinos
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
| | - Christian Tesche
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
- Department of Cardiology, Munich University Clinic, Ludwig-Maximilians-University, Marchioninistr. 15, 81377 Munich, Germany
| | - Jens Ricke
- Department of Radiology, University Hospital, LMU Munich, Marchioninistr. 15, 81377 Munich, Germany
| | - Martin J Willemink
- Department of Radiology, Stanford University School of Medicine, 291 Campus Drive, Stanford, CA 94305, USA
| | - Akos Varga-Szemes
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
| | - Tilman Emrich
- Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Medical University of South Carolina, 25 Courtenay Dr, Charleston, SC 29425, USA
- Department of Diagnostic and Interventional Radiology, University Medical Center of Johannes-Gutenberg-University, Langenbeckstr. 1, 55131 Mainz, Germany
- German Centre for Cardiovascular Research, Partner Site Rhine-Main, 55131 Mainz, Germany
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van der Bie J, van Straten M, Booij R, Bos D, Dijkshoorn ML, Hirsch A, Sharma SP, Oei EHG, Budde RPJ. Photon-counting CT: Review of initial clinical results. Eur J Radiol 2023; 163:110829. [PMID: 37080060 DOI: 10.1016/j.ejrad.2023.110829] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 04/05/2023] [Indexed: 04/22/2023]
Abstract
Photon-counting computed tomography (PCCT) is a new technology that enables higher spatial resolution compared to conventional CT techniques, energy resolved imaging and spectral post-processing. This leads to improved contrast-to-noise ratio, artifact and potential dose reduction as well as elimination of electronic noise. Since the introduction of clinical PCCT in 2021, a shift has been observed from solely pre-clinical studies to clinical research (i.e. use of PCCT imaging in humans). This review article is focused on the initial clinical results of PCCT by explaining the current PCCT systems, the applications themselves and, the challenges of PCCT.
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Affiliation(s)
- Judith van der Bie
- Department of Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
| | - Marcel van Straten
- Department of Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
| | - Ronald Booij
- Department of Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
| | - Daniel Bos
- Department of Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands; Department of Epidemiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
| | - Marcel L Dijkshoorn
- Department of Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
| | - Alexander Hirsch
- Department of Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands; Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
| | - Simran P Sharma
- Department of Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands; Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
| | - Edwin H G Oei
- Department of Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
| | - Ricardo P J Budde
- Department of Radiology & Nuclear Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands.
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Deleu M, Maurice JB, Devos L, Remy M, Dubus F. Image Quality Analysis of Photon-Counting CT Compared with Dual-Source CT: A Phantom Study for Chest CT Examinations. Diagnostics (Basel) 2023; 13:diagnostics13071325. [PMID: 37046543 PMCID: PMC10092985 DOI: 10.3390/diagnostics13071325] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/27/2023] [Accepted: 03/29/2023] [Indexed: 04/05/2023] Open
Abstract
A comparison was made between the image quality of a photon-counting CT (PCCT) and a dual-source CT (DSCT). The evaluation of image quality was performed using a Catphan CT phantom, and the physical metrics, such as the noise power spectrum and task transfer function, were measured for both PCCT and DSCT at three CT dose indices (1, 5 and 10 mGy). Polyenergetic and virtual monoenergetic reconstructions were used to evaluate the performance differences by simulating a Gaussian spot with a radius of 5 mm and calculating the detectability index. The highest iterative reconstruction level was able to decrease the noise by about 70% compared with the filtered back projection using a parenchyma reconstruction kernel. The PCCT task transfer functions remained constant, while those of the DSCT increased with the reconstruction strength level. At monoenergetic 70 keV, a 50% decrease in noise was observed for DSCT with image smoothing, while PCCT had the same 50% decrease in noise without any smoothing. The PCCT detectability index at a reconstruction strength level of two was equivalent to the highest level of ADMIRE 5 for DSCT. The PCCT showed its superiority over the DSCT, especially for lung nodule detection.
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Affiliation(s)
- Marine Deleu
- Medical Physics Department, University Hospital, 59037 Lille, France
| | | | - Laura Devos
- Medical Physics Department, University Hospital, 59037 Lille, France
| | - Martine Remy
- Radiology Department, Heart-Lung Institute, University Hospital, 59037 Lille, France
| | - François Dubus
- Medical Physics Department, University Hospital, 59037 Lille, France
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Baffour FI, Glazebrook KN, Ferrero A, Leng S, McCollough CH, Fletcher JG, Rajendran K. Photon-Counting Detector CT for Musculoskeletal Imaging: A Clinical Perspective. AJR Am J Roentgenol 2023; 220:551-560. [PMID: 36259593 DOI: 10.2214/ajr.22.28418] [Citation(s) in RCA: 34] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Photon-counting detector (PCD) CT has emerged as a novel imaging modality that represents a fundamental shift in the way that CT systems detect x-rays. After pre-clinical and clinical investigations showed benefits of PCD CT for a range of imaging tasks, the U.S. FDA in 2021 approved the first commercial PCD CT system for clinical use. The technologic features of PCD CT are particularly well suited for musculo-skeletal imaging applications. Advantages of PCD CT compared with conventional energy-integrating detector (EID) CT include smaller detector pixels and excellent geometric dose efficiency that enable imaging of large joints and central skeletal anatomy at ultrahigh spatial resolution; advanced multienergy spectral postprocessing that allows quantification of gout deposits and generation of virtual noncalcium images for visualization of bone edema; improved metal artifact reduction for imaging of orthopedic implants; and higher CNR and suppression of electronic noise. Given substantially improved cortical and trabecular detail, PCD CT images more clearly depict skeletal abnormalities, including fractures, lytic lesions, and mineralized tumor matrix. The purpose of this article is to review, by use of clinical examples comparing EID CT and PCD CT, the technical features of PCD CT and their associated impact on musculoskeletal imaging applications.
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Affiliation(s)
- Francis I Baffour
- Department of Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905
| | | | - Andrea Ferrero
- Department of Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905
| | - Shuai Leng
- Department of Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905
| | | | - Joel G Fletcher
- Department of Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905
| | - Kishore Rajendran
- Department of Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905
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Myeloma bone disease imaging on a 1st-generation clinical photon-counting detector CT vs. 2nd-generation dual-source dual-energy CT. Eur Radiol 2023; 33:2415-2425. [PMID: 36350390 PMCID: PMC10017628 DOI: 10.1007/s00330-022-09225-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 09/22/2022] [Accepted: 10/19/2022] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Subjective and objective image quality comparison of bone microstructure and disease-related abnormalities in multiple myeloma patients using a 1st-generation dual-source photon-counting detector CT(DS-PCD-CT) and a 2nd-generation dual-source dual-energy (energy-integrating detector) CT (DS-EID-CT). METHODS Fifty multiple myeloma patients (mean age 67.7 ± 10.9 years,16 females) were prospectively enrolled. Unenhanced whole-body CTs were clinically indicated and performed on DS-EID-CT and DS-PCD-CT (median time difference: 12 months). DS-PCD-CT was performed in Quantumplus UHR mode and DS-EID-CT was performed using dual-energy mode. DS-PCD-CT kernel was set at Br64 with Quantum iterative reconstruction strength Q1; for DS-EID-CT a comparable I70f kernel with SAFIRE iterative reconstruction strength 1 was used. Two independent radiologists assessed image quality subjectively using a 5-point Likert scale considering delineation and sharpness of trabecular bone and lytic bone lesions in the spine and pelvic bones. Additionally, ImageJ was used for quantification of bony septa inside the cancellous bone and through or the edges of osteolysis. RESULTS Overall quality as well as detectability and sharpness in the delineation of lytic bone lesions were superior for DS-PCD-CT compared with DS-EID-CT (p < 0.0001). The inter-reader agreement for subjective image quality readings showed excellent consistency(α = 94.2-98.8). CTDI and DLP mean values for DS-PCD-CT and DS-EID-CT were 1107.4 ± 247.6 mGy*cm and 8.2 ± 1.8 mGy vs. 1344.3 ± 204.6 mGy*cm and 10.1 ± 1.9 mGy. The quantitative metric for bone microstructure in the femoral head showed significantly better visualization of trabeculae in DS-PCD-CT compared with DS-EID-CT (p < 0.0001). Quantitative analyses of edge sharpness of osteolysis showed significant steeper edges for DS-PCD-CT (p < 0.0001). CONCLUSION DS-PCD-CT significantly improves spatial resolution of bony microstructure and lytic bone lesions compared to DS-EID-CT. KEY POINTS • Application of photon-counting detector CT is superior to dual-source dual-energy integrating detector in clinical workup of multiple myeloma patients. • Compared to energy integrating detectors, photon-counting detectors significantly increase the spatial resolution of bone microstructure including disease-related lytic bone lesions in patients with multiple myeloma.
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Racine D, Mergen V, Viry A, Eberhard M, Becce F, Rotzinger DC, Alkadhi H, Euler A. Photon-Counting Detector CT With Quantum Iterative Reconstruction: Impact on Liver Lesion Detection and Radiation Dose Reduction. Invest Radiol 2023; 58:245-252. [PMID: 36094810 DOI: 10.1097/rli.0000000000000925] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To assess image noise, diagnostic performance, and potential for radiation dose reduction of photon-counting detector (PCD) computed tomography (CT) with quantum iterative reconstruction (QIR) in the detection of hypoattenuating and hyperattenuating focal liver lesions compared with energy-integrating detector (EID) CT. MATERIALS AND METHODS A medium-sized anthropomorphic abdominal phantom with liver parenchyma and lesions (diameter, 5-10 mm; hypoattenuating and hyperattenuating from -30 HU to +90 HU at 120 kVp) was used. The phantom was imaged on ( a ) a third-generation dual-source EID-CT (SOMATOM Force, Siemens Healthineers) in the dual-energy mode at 100 and 150 kVp with tin filtration and ( b ) a clinical dual-source PCD-CT at 120 kVp (NAEOTOM Alpha, Siemens). Scans were repeated 10 times for each of 3 different radiation doses of 5, 2.5, and 1.25 mGy. Datasets were reconstructed as virtual monoenergetic images (VMIs) at 60 keV for both scanners and as linear-blended images (LBIs) for EID-CT. For PCD-CT, VMIs were reconstructed with different strength levels of QIR (QIR 1-4) and without QIR (QIR-off). For EID-CT, VMIs and LBIs were reconstructed using advanced modeled iterative reconstruction at a strength level of 3. Noise power spectrum was measured to compare image noise magnitude and texture. A channelized Hotelling model observer was used to assess diagnostic accuracy for lesion detection. The potential for radiation dose reduction using PCD-CT was estimated for the QIR strength level with the highest area under the curve compared with EID-CT for each radiation dose. RESULTS Image noise decreased with increasing QIR level at all radiation doses. Using QIR-4, noise reduction was 41%, 45%, and 59% compared with EID-CT VMIs and 12%, 18%, and 33% compared with EID-CT LBIs at 5, 2.5, and 1.25 mGy, respectively. The peak spatial frequency shifted slightly to lower frequencies at higher QIR levels. Lesion detection accuracy increased at higher QIR levels and was higher for PCD-CT compared with EID-CT VMIs. The improvement in detection with PCD-CT was strongest at the lowest radiation dose, with an area under the receiver operating curve of 0.917 for QIR-4 versus 0.677 for EID-CT VMIs for hyperattenuating lesions, and 0.900 for QIR-4 versus 0.726 for EID-CT VMIs for hypoattenuating lesions. Compared with EID-CT LBIs, detection was higher for QIR 1-4 at 2.5 mGy and for QIR 2-4 at 1.25 mGy (eg, 0.900 for QIR-4 compared with 0.854 for EID-CT LBIs at 1.25 mGy). Radiation dose reduction potential of PCD-CT with QIR-4 was 54% at 5 mGy compared with VMIs and 39% at 2.5 mGy compared with LBIs. CONCLUSIONS Compared with EID-CT, PCD-CT with QIR substantially improved focal liver lesion detection, especially at low radiation dose. This enables substantial radiation dose reduction while maintaining diagnostic accuracy.
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Affiliation(s)
- Damien Racine
- From the Institute of Radiation Physics (IRA), Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne
| | - Victor Mergen
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich
| | - Anaïs Viry
- From the Institute of Radiation Physics (IRA), Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne
| | - Matthias Eberhard
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich
| | - Fabio Becce
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
| | - David C Rotzinger
- Department of Diagnostic and Interventional Radiology, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), Lausanne, Switzerland
| | - Hatem Alkadhi
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich
| | - André Euler
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich
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Dillinger D, Overhoff D, Booz C, Kaatsch HL, Piechotka J, Hagen A, Froelich MF, Vogl TJ, Waldeck S. Impact of CT Photon-Counting Virtual Monoenergetic Imaging on Visualization of Abdominal Arterial Vessels. Diagnostics (Basel) 2023; 13:diagnostics13050938. [PMID: 36900082 PMCID: PMC10000913 DOI: 10.3390/diagnostics13050938] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/20/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023] Open
Abstract
PURPOSE The novel photon-counting detector (PCD) technique acquires spectral data for virtual monoenergetic imaging (VMI) in every examination. The aim of this study was the evaluation of the impact of VMI of abdominal arterial vessels on quantitative and qualitative subjective image parameters. METHODS A total of 20 patients that underwent an arterial phase computed tomography (CT) scan of the abdomen with a novel PCD CT (Siemens NAEOTOM alpha) were analyzed regarding attenuation at different energy levels in virtual monoenergetic imaging. Contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were calculated and compared between the different virtual monoenergetic (VME) levels with correlation to vessel diameter. In addition, subjective image parameters (overall subjective image quality, subjective image noise and vessel contrast) were evaluated. RESULTS Our research showed decreasing attenuation levels with increasing energy levels in virtual monoenergetic imaging regardless of vessel diameter. CNR showed best overall results at 60 keV, and SNR at 70 keV with no significant difference to 60 keV (p = 0.294). Subjective image quality was rated best at 70 keV for overall image quality, vessel contrast and noise. CONCLUSIONS Our data suggest that VMI at 60-70 keV provides the best objective and subjective image quality concerning vessel contrast irrespective of vessel size.
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Affiliation(s)
- Daniel Dillinger
- Department of Vascular Surgery and Endovascular Surgery, Bundeswehr Central Hospital, Rübenacher Straße 170, 56072 Koblenz, Germany
- Correspondence:
| | - Daniel Overhoff
- Department of Radiology and Neuroradiology, Bundeswehr Central Hospital, Rübenacher Straße 170, 56072 Koblenz, Germany
- Department of Radiology and Nuclear Medicine, University Medical Centre Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Christian Booz
- Institute for Diagnostic and Interventional Radiology, Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany
| | - Hanns L. Kaatsch
- Department of Radiology and Neuroradiology, Bundeswehr Central Hospital, Rübenacher Straße 170, 56072 Koblenz, Germany
| | - Joel Piechotka
- Department of Radiology and Neuroradiology, Bundeswehr Central Hospital, Rübenacher Straße 170, 56072 Koblenz, Germany
| | - Achim Hagen
- Department of Vascular Surgery and Endovascular Surgery, Bundeswehr Central Hospital, Rübenacher Straße 170, 56072 Koblenz, Germany
| | - Matthias F. Froelich
- Department of Radiology and Nuclear Medicine, University Medical Centre Mannheim, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Thomas J. Vogl
- Institute for Diagnostic and Interventional Radiology, Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany
| | - Stephan Waldeck
- Department of Radiology and Neuroradiology, Bundeswehr Central Hospital, Rübenacher Straße 170, 56072 Koblenz, Germany
- Department of Neuroradiology, University Medical Center Mainz, Langenbeckstraße 1, 55131 Mainz, Germany
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Sartoretti T, McDermott M, Mergen V, Euler A, Schmidt B, Jost G, Wildberger JE, Alkadhi H. Photon-counting detector coronary CT angiography: impact of virtual monoenergetic imaging and iterative reconstruction on image quality. Br J Radiol 2023; 96:20220466. [PMID: 36633005 PMCID: PMC9975359 DOI: 10.1259/bjr.20220466] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 09/30/2022] [Accepted: 11/08/2022] [Indexed: 01/13/2023] Open
Abstract
OBJECTIVES To assess the impact of low kilo-electronvolt (keV) virtual monoenergetic image (VMI) energies and iterative reconstruction on image quality of clinical photon-counting detector coronary CT angiography (CCTA). METHODS CCTA with PCD-CT (prospective ECG-triggering, 120 kVp, automatic tube current modulation) was performed in a high-end cardiovascular phantom with dynamic flow, pulsatile heart motion, and including different calcified plaques with various stenosis grades and in 10 consecutive patients. VMI at 40,50,60 and 70 keV were reconstructed without (QIR-off) and with all quantum iterative reconstruction (QIR) levels (QIR-1 to 4). In the phantom, noise power spectrum, vessel attenuation, contrast-to-noise-ratio (CNR), and vessel sharpness were measured. Two readers graded stenoses in the phantom and graded overall image quality, subjective noise, vessel sharpness, vascular contrast, and coronary artery plaque delineation on 5-point Likert scales in patients. RESULTS In the phantom, noise texture was only slightly affected by keV and QIR while noise increased by 69% from 70 keV QIR-4 to 40 keV QIR-off. Reconstructions at 40 keV QIR-4 exhibited the highest CNR (46.1 ± 1.8), vessel sharpness (425 ± 42 ∆HU/mm), and vessel attenuation (1098 ± 14 HU). Stenosis measurements were not affected by keV or QIR level (p > 0.12) with an average error of 3%/6% for reader 1/reader 2, respectively. In patients, across all subjective categories and both readers, 40 keV QIR-3 and QIR-4 images received the best scores (p < 0.001). CONCLUSION Forty keV VMI with QIR-4 significantly improved image quality of CCTA with PCD-CT. ADVANCES IN KNOWLEDGE PCD-CT at 40 keV and QIR-4 improves image quality of CCTA.
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Affiliation(s)
| | | | - Victor Mergen
- Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - André Euler
- Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | | | | | | | - Hatem Alkadhi
- Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
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Conrads N, Grunz JP, Huflage H, Luetkens KS, Feldle P, Pennig L, Ergün S, Alexander Bley T, Petritsch B, Kunz AS. Ultrahigh-resolution computed tomography of the cervical spine without dose penalty employing a cadmium-telluride photon-counting detector. Eur J Radiol 2023; 160:110718. [PMID: 36731400 DOI: 10.1016/j.ejrad.2023.110718] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 01/18/2023] [Accepted: 01/25/2023] [Indexed: 01/28/2023]
Abstract
PURPOSE This cadaveric study compared image quality between a third-generation dual-source CT scanner with energy-integrating detector technology (EID) and a first-generation CT system employing a photon-counting detector (PCD) for the cervical spine in ultrahigh-resolution mode. METHODS The cervical spine of eight formalin-fixed full-body cadaveric specimens was scanned with both CT systems using 140 kVp scan protocols matched for CTDIvol (full-dose; low-dose; ultralow-dose; 10 mGy; 3 mGy; 1 mGy). Images were reconstructed with 1 mm slice thickness and 0.5 mm increment. Three radiologists rated overall subjective image quality based on an equidistant five-point scale with the intraclass correlation coefficient (ICC) calculated for assessment of interobserver reliability. Contrast-to-noise ratios were calculated individually for bone (CNRbone) and muscle tissue (CNRmuscle) to provide objective criteria of image analysis. RESULTS Subjective image quality, as well as CNRbone, and CNRmuscle were each superior for PCD-CT compared to EID-CT among dose-matched scan protocol pairs (all p < 0.05). Between full-dose EID-CT and low-dose PCD-CT, subjective image quality was equal (p = 0.903), while superior quantitative results regarding the latter were ascertained (both p < 0.001). Similarly, objective analysis determined higher CNRbone, and CNRmuscle in ultralow-dose PCD-CT compared to low-dose EID-CT (both p < 0.001), while readers considered the image quality of the respective studies comparable (p > 0.99). Interobserver reliability was good, denoted by an ICC of 0.861 (95 % confidence interval: 0.788 - 0.914; p < 0.001). CONCLUSIONS In cervical spine examinations, both subjective and objective image quality of PCD-CT were superior to EID-CT in comparison of scan protocols with corresponding dose levels, suggesting potential for significantly reducing the radiation exposure without compromising image quality.
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Affiliation(s)
- Nora Conrads
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany.
| | - Jan-Peter Grunz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Henner Huflage
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Karsten Sebastian Luetkens
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Philipp Feldle
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Lenhard Pennig
- Institute for Diagnostic and Interventional Radiology, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Straße 62, 50937 Cologne, Germany
| | - Süleyman Ergün
- Institute of Anatomy and Cell Biology, University of Würzburg, Koellikerstraße 6, 97070 Würzburg, Germany
| | - Thorsten Alexander Bley
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Bernhard Petritsch
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
| | - Andreas Steven Kunz
- Department of Diagnostic and Interventional Radiology, University Hospital Würzburg, Oberdürrbacher Straße 6, 97080 Würzburg, Germany
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Sartoretti T, Mergen V, Jungblut L, Alkadhi H, Euler A. Liver Iodine Quantification With Photon-Counting Detector CT: Accuracy in an Abdominal Phantom and Feasibility in Patients. Acad Radiol 2023; 30:461-469. [PMID: 35644755 DOI: 10.1016/j.acra.2022.04.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 04/12/2022] [Accepted: 04/21/2022] [Indexed: 01/25/2023]
Abstract
RATIONALE AND OBJECTIVES To compare the accuracy of iodine quantification in liver parenchyma and lesions between dual-source photon-counting detector CT (PCD-CT) and dual-source energy-integrating detector CT (EID-CT) in a phantom and to demonstrate the feasibility of iodine quantification with PCD-CT in liver parenchyma and lesions in patients. MATERIALS AND METHODS An anthropomorphic abdominal phantom with a liver insert containing parenchyma and lesions was imaged on a clinical PCD-CT at 120kV and in the dual-energy mode on an EID-CT with kV-combinations of 80/Sn150kV, 90/Sn150kV, and 100/Sn150kV. Three patient sizes were imaged at three different radiation doses (CTDIvol: 5, 10, 15mGy). Thirty patients with liver cysts, hemangiomas or metastases imaged with PCD-CT were retrospectively included. Iodine maps were reconstructed and iodine concentrations were measured in liver parenchyma and lesions. For the phantom, iodine error was quantified as the absolute difference to the vendor's specifications as reference. RESULTS Overall iodine error was 0.33 ± 0.29, 0.34 ± 0.32, 0.39 ± 0.37, 0.35 ± 0.39 mgI/mL for 80/Sn150kV, 90/Sn150kV, 100/Sn150kV of EID-CT, and PCD-CT, respectively, without significant differences between PCD-CT and EID-CT (p > 0.05). Radiation dose did not significantly influence error of PCD-CT (p > 0.05) nor EID-CT (p > 0.05). For both scanners, smaller patient sizes were associated with lower errors (p < 0.05). Iodine concentration and base material attenuation significantly influenced quantification for EID-CT (p < 0.05) but not PCD-CT (p > 0.05). In patients, iodine quantification was feasible in liver parenchyma, cysts, hemangiomas, and metastases. CONCLUSION Iodine quantification with PCD-CT is accurate in simulated liver parenchyma and lesions irrespective of radiation dose, iodine concentration, and base attenuation and is feasible in common liver lesions in patients.
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Affiliation(s)
- Thomas Sartoretti
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Raemistrasse 100, CH-809, Zurich, Switzerland
| | - Victor Mergen
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Raemistrasse 100, CH-809, Zurich, Switzerland
| | - Lisa Jungblut
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Raemistrasse 100, CH-809, Zurich, Switzerland
| | - Hatem Alkadhi
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Raemistrasse 100, CH-809, Zurich, Switzerland
| | - André Euler
- Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Raemistrasse 100, CH-809, Zurich, Switzerland.
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Sartoretti T, Wildberger JE, Flohr T, Alkadhi H. Photon-counting detector CT: early clinical experience review. Br J Radiol 2023:20220544. [PMID: 36744809 DOI: 10.1259/bjr.20220544] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Since its development in the 1970s, X-ray CT has emerged as a landmark diagnostic imaging modality of modern medicine. Technological advances have been crucial to the success of CT imaging, as they have increasingly enabled improvements in image quality and diagnostic value at increasing radiation dose efficiency. With recent advances in engineering and physics, a novel technology has emerged with the potential to surpass several shortcomings and limitations of current CT systems. Photon-counting detector (PCD)-CT might substantially improve and expand the applicability of CT imaging by offering intrinsic spectral capabilities, increased spatial resolution, reduced electronic noise and improved image contrast. In this review we sought to summarize the first clinical experience of PCD-CT. We focused on most recent prototype and first clinically approved PCD-CT systems thereby reviewing initial publications and presenting corresponding clinical cases.
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Affiliation(s)
- Thomas Sartoretti
- Diagnostic and Interventional Radiology, University Hospital Zürich, University of Zürich, Zürich, Switzerland.,Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands.,Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - Joachim E Wildberger
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center, Maastricht, The Netherlands.,Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands
| | - Thomas Flohr
- Siemens Healthcare GmbH, Computed Tomography, Forchheim, Germany
| | - Hatem Alkadhi
- Diagnostic and Interventional Radiology, University Hospital Zürich, University of Zürich, Zürich, Switzerland
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Potential of Unenhanced Ultra-Low-Dose Abdominal Photon-Counting CT with Tin Filtration: A Cadaveric Study. Diagnostics (Basel) 2023; 13:diagnostics13040603. [PMID: 36832091 PMCID: PMC9955485 DOI: 10.3390/diagnostics13040603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/28/2023] [Accepted: 02/04/2023] [Indexed: 02/10/2023] Open
Abstract
OBJECTIVES This study investigated the feasibility and image quality of ultra-low-dose unenhanced abdominal CT using photon-counting detector technology and tin prefiltration. MATERIALS AND METHODS Employing a first-generation photon-counting CT scanner, eight cadaveric specimens were examined both with tin prefiltration (Sn 100 kVp) and polychromatic (120 kVp) scan protocols matched for radiation dose at three different levels: standard-dose (3 mGy), low-dose (1 mGy) and ultra-low-dose (0.5 mGy). Image quality was evaluated quantitatively by means of contrast-to-noise-ratios (CNR) with regions of interest placed in the renal cortex and subcutaneous fat. Additionally, three independent radiologists performed subjective evaluation of image quality. The intraclass correlation coefficient was calculated as a measure of interrater reliability. RESULTS Irrespective of scan mode, CNR in the renal cortex decreased with lower radiation dose. Despite similar mean energy of the applied x-ray spectrum, CNR was superior for Sn 100 kVp over 120 kVp at standard-dose (17.75 ± 3.51 vs. 14.13 ± 4.02), low-dose (13.99 ± 2.6 vs. 10.68 ± 2.17) and ultra-low-dose levels (8.88 ± 2.01 vs. 11.06 ± 1.74) (all p ≤ 0.05). Subjective image quality was highest for both standard-dose protocols (score 5; interquartile range 5-5). While no difference was ascertained between Sn 100 kVp and 120 kVp examinations at standard and low-dose levels, the subjective image quality of tin-filtered scans was superior to 120 kVp with ultra-low radiation dose (p < 0.05). An intraclass correlation coefficient of 0.844 (95% confidence interval 0.763-0.906; p < 0.001) indicated good interrater reliability. CONCLUSIONS Photon-counting detector CT permits excellent image quality in unenhanced abdominal CT with very low radiation dose. Employment of tin prefiltration at 100 kVp instead of polychromatic imaging at 120 kVp increases the image quality even further in the ultra-low-dose range of 0.5 mGy.
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Moy L. Top Publications in Radiology, 2022. Radiology 2023; 306:e222914. [PMID: 36625749 DOI: 10.1148/radiol.222914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Reduced Iodinated Contrast Media Administration in Coronary CT Angiography on a Clinical Photon-Counting Detector CT System: A Phantom Study Using a Dynamic Circulation Model. Invest Radiol 2023; 58:148-155. [PMID: 36165932 DOI: 10.1097/rli.0000000000000911] [Citation(s) in RCA: 33] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
PURPOSE The aim of this study was to evaluate strategies to reduce contrast media volumes for coronary computed tomography (CT) angiography on a clinical first-generation dual-source photon-counting detector (PCD)-CT system using a dynamic circulation phantom. MATERIALS AND METHODS Coronary CT angiograph is an established method for the assessment of coronary artery disease that relies on the administration of iodinated contrast media. Reduction of contrast media volumes while maintaining diagnostic image quality is desirable. In this study, a dynamic phantom containing a 3-dimensional-printed model of the thoracic aorta and coronary arteries was evaluated using a clinical contrast injection protocol with stepwise reduced contrast agent concentrations (100%, 75%, 50%, 40%, 30%, and 20% contrast media content of the same 50 mL bolus, resulting in iodine delivery rates of 1.5, 1.1, 0.7, 0.6, 0.4 and 0.3 gl/s) on a first-generation, dual-source PCD-CT. Polychromatic images (T3D) and virtual monoenergetic images were reconstructed in the range of 40 to 70 keV in 5-keV steps. Attenuation and noise were measured in the coronary arteries and background material and the contrast-to-noise ratio (CNR) were calculated. Attenuation of 350 HU and a CNR of the reference protocol at 70 keV were regarded as sufficient for simulation of diagnostic purposes. Vessel sharpness and noise power spectra were analyzed for the aforementioned reconstructions. RESULTS The standard clinical contrast protocol (bolus with 100% contrast) yielded diagnostic coronary artery attenuation for all tested reconstructions (>398 HU). A 50% reduction in contrast media concentration demonstrated sufficient attenuation of the coronary arteries at 40 to 55 keV (>366 HU). Virtual monoenergetic image reconstructions of 40 to 45 and 40 keV allowed satisfactory attenuation of the coronary arteries for contrast concentrations of 40% and 30% of the original protocol. A reduction of contrast agent concentration to 20% of the initial concentration provided insufficient attenuation in the target vessels for all reconstructions. The highest CNR was found for virtual monoenergetic reconstructions at 40 keV for all contrast media injection protocols, yielding a sufficient CNR at a 50% reduction of contrast agent concentration. CONCLUSIONS Using virtual monoenergetic image reconstructions at 40 keV on a dual-source PCD-CT system, contrast media concentration could be reduced by 50% to obtain diagnostic attenuation and objective image quality for coronary CT angiography in a dynamic vessel phantom. These initial feasibility study results have to be validated in clinical studies.
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Higashigaito K, Mergen V, Eberhard M, Jungblut L, Hebeisen M, Rätzer S, Zanini B, Kobe A, Martini K, Euler A, Alkadhi H. CT Angiography of the Aorta Using Photon-counting Detector CT with Reduced Contrast Media Volume. Radiol Cardiothorac Imaging 2023; 5:e220140. [PMID: 36860835 PMCID: PMC9969214 DOI: 10.1148/ryct.220140] [Citation(s) in RCA: 33] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 12/04/2022] [Accepted: 12/14/2022] [Indexed: 01/27/2023]
Abstract
Purpose To develop and evaluate a low-volume contrast media protocol for thoracoabdominal CT angiography (CTA) with photon-counting detector (PCD) CT. Materials and Methods This prospective study included consecutive participants (April-September 2021) who underwent CTA with PCD CT of the thoracoabdominal aorta and previous CTA with energy-integrating detector (EID) CT at equal radiation doses. In PCD CT, virtual monoenergetic images (VMI) were reconstructed in 5-keV intervals from 40 to 60 keV. Attenuation of the aorta, image noise, and contrast-to-noise ratio (CNR) were measured, and subjective image quality was rated by two independent readers. In the first group of participants, the same contrast media protocol was used for both scans. CNR gain in PCD CT compared with EID CT served as the reference for contrast media volume reduction in the second group. Noninferiority analysis was used to test noninferior image quality of the low-volume contrast media protocol with PCD CT. Results The study included 100 participants (mean age, 75 years ± 8 [SD]; 83 men). In the first group (n = 40), VMI at 50 keV provided the best trade-off between objective and subjective image quality, achieving 25% higher CNR compared with EID CT. Contrast media volume in the second group (n = 60) was reduced by 25% (52.5 mL). Mean differences in CNR and subjective image quality between EID CT and PCD CT at 50 keV were above the predefined boundaries of noninferiority (-0.54 [95% CI: -1.71, 0.62] and -0.36 [95% CI: -0.41, -0.31], respectively). Conclusion CTA of the aorta with PCD CT was associated with higher CNR, which was translated into a low-volume contrast media protocol demonstrating noninferior image quality compared with EID CT at the same radiation dose.Keywords: CT Angiography, CT-Spectral, Vascular, Aorta, Contrast Agents-Intravenous, Technology Assessment© RSNA, 2023See also the commentary by Dundas and Leipsic in this issue.
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Affiliation(s)
- Kai Higashigaito
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Rämistrasse 100, 8091 Zürich, Switzerland (K.H., V.M., M.E., L.J., S.R., B.Z., A.K., K.M., A.E., H.A.); and Department of Biostatistics at Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Switzerland (M.H.)
| | - Victor Mergen
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Rämistrasse 100, 8091 Zürich, Switzerland (K.H., V.M., M.E., L.J., S.R., B.Z., A.K., K.M., A.E., H.A.); and Department of Biostatistics at Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Switzerland (M.H.)
| | - Matthias Eberhard
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Rämistrasse 100, 8091 Zürich, Switzerland (K.H., V.M., M.E., L.J., S.R., B.Z., A.K., K.M., A.E., H.A.); and Department of Biostatistics at Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Switzerland (M.H.)
| | - Lisa Jungblut
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Rämistrasse 100, 8091 Zürich, Switzerland (K.H., V.M., M.E., L.J., S.R., B.Z., A.K., K.M., A.E., H.A.); and Department of Biostatistics at Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Switzerland (M.H.)
| | - Monika Hebeisen
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Rämistrasse 100, 8091 Zürich, Switzerland (K.H., V.M., M.E., L.J., S.R., B.Z., A.K., K.M., A.E., H.A.); and Department of Biostatistics at Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Switzerland (M.H.)
| | - Susan Rätzer
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Rämistrasse 100, 8091 Zürich, Switzerland (K.H., V.M., M.E., L.J., S.R., B.Z., A.K., K.M., A.E., H.A.); and Department of Biostatistics at Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Switzerland (M.H.)
| | - Bettina Zanini
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Rämistrasse 100, 8091 Zürich, Switzerland (K.H., V.M., M.E., L.J., S.R., B.Z., A.K., K.M., A.E., H.A.); and Department of Biostatistics at Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Switzerland (M.H.)
| | - Adrian Kobe
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Rämistrasse 100, 8091 Zürich, Switzerland (K.H., V.M., M.E., L.J., S.R., B.Z., A.K., K.M., A.E., H.A.); and Department of Biostatistics at Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Switzerland (M.H.)
| | - Katharina Martini
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Rämistrasse 100, 8091 Zürich, Switzerland (K.H., V.M., M.E., L.J., S.R., B.Z., A.K., K.M., A.E., H.A.); and Department of Biostatistics at Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Switzerland (M.H.)
| | - André Euler
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Rämistrasse 100, 8091 Zürich, Switzerland (K.H., V.M., M.E., L.J., S.R., B.Z., A.K., K.M., A.E., H.A.); and Department of Biostatistics at Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Switzerland (M.H.)
| | - Hatem Alkadhi
- From the Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, University of Zurich, Rämistrasse 100, 8091 Zürich, Switzerland (K.H., V.M., M.E., L.J., S.R., B.Z., A.K., K.M., A.E., H.A.); and Department of Biostatistics at Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Switzerland (M.H.)
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